Siemens simatic S7-1200. Manual (2015)

PID is easy

8.11 Commissioning the PID_Temp controller

PID parameters

The “Advanced settings” view, "PID Parameters” section is shown below with the cooling

and/or “PID parameterswitchover” feature deactivated.

Setting

TO-DB parameter

Data

Value range

Description

type

Enable

"Retain.CtrlParams.

Bool

You must check this

SetByUser"

checkbox to enter PID

manual

parameters manually.

entry

Proportional

"Retain.CtrlParams.

Real

Gain >= 0.0

PID proportional gain

gain (heat-

Heat.Gain"

for heating

ing) ²

Integral

"Retain.CtrlParams.

Real

100000.0 >=

PID integral action for

action time

Heat.Ti"

Ti >= 0.0

heating.

(heating) ^1,2

Derivative

"Retain.CtrlParams.

Real

100000.0 >=

PID derivative action

action time

Heat.Td"

Td >= 0.0

time for heating.

(heating)^1,2

Derivative

"Retain.CtrlParams.

Real

TdFiltRatio >=

PID derivative delay

delay coeffi-

Heat.TdFiltRatio"

0.0

coefficient for heating

cient(heatin

that defines the deriva-

g) ²

tive lag time as coeffi-

cient from the PID

derivative time.

Proportional

"Retain.CtrlParams.

Real

1.0 >=PWeighting

Weighting of the PID

action

Heat.PWeighting"

>= 0.0

proportional gain for

weighting(h

heating in either direct-

eating) ²

or loopback- control

path.

Derivative

"Retain.CtrlParams.

Real

1.0 >=DWeighting

Weighting of the PID

action

Heat.DWeighting"

>= 0.0

derivative part for heat-

weighting

ing in either direct- or

(heating) ²

loopback- control path.

243

PID is easy

8.11 Commissioning the PID_Temp controller

Setting

TO-DB parameter

Data

Value range

Description

type

Sampling

"Retain.CtrlParams.

Real

100000.0

Internal call cycle of the

time of PID

Heat.Cycle"

>=Cycle

PID controller for heat-

algorithm

> 0.0

ing.

(heating) ^1,2

Rounded to an integer

multiple of the FB call

cycle time.

Deadband

"Retain.CtrlParams.

Real

DeadZone>= 0.0

Width of the deadband

width(heatin

Heat.DeadZone"

for heating control

g) ^2,3

deviation.

Control

"Retain.CtrlParams.

Real

ControlZone> 0.0

Width of the control

Zone (heat-

Heat.ControlZone"

deviation zone for heat-

ing)^2,3

ing where PID control is

active. If control devia-

tion leaves this range,

output is switched to

maximum output val-

ues.

Default value is

"MaxReal" so control

zone is deactivated as

long as autotuning is

not executed.

Value "0.0" is prohibit-

ed for Control Zone;

with the value "0.0",

PID_Temp behaves like

a two-position controller

that is always heating

or cooling at full power.

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PID is easy

8.11 Commissioning the PID_Temp controller

Setting

TO-DB parameter

Data

Value range

Description

type

Controller

"PIDSelfTune.SUT.

Int

"PIDSelf-

You can select the

structure

TuneRuleHeat",

Tune.SUT.

tuning algorithm for

(heating)

TuneRuleHeat"

heating.

"PIDSelfTune.TIR.

= 0..2,

TuneRuleHeat"

Possible selections:

"PIDSelf-

• PID (Temperature)

Tune.TIR.

(=default)

TuneRuleHeat"

= 0..5

("PIDSelfTune.SUT.

TuneRuleHeat" = 2)

("PIDSelfTune.TIR.

TuneRuleHeat" = 0)

• PID

("PIDSelfTune.SUT.

TuneRuleHeat" = 0)

("PIDSelfTune.TIR.

TuneRuleHeat" = 0)

• PI

("PIDSelfTune.SUT.

TuneRuleHeat" = 1)

("PIDSelfTune.TIR.

TuneRuleHeat" = 4)

Any other combination

shows “User defined”,

but “User defined” is

not provided by default.

“PID (Temperature)” is

new for PID_Temp,

with a specific pretun-

ing (SUT) method for

temperature processes.

Proportional

"Retain.CtrlParams.

Real

Gain >= 0.0

PID proportional gain

gain (cool-

Cool.Gain"

for cooling

ing) ⁴

Integral

"Retain.CtrlParams.

Real

100000.0 >=Ti

PID integral action for

action time

Cool.Ti"

>= 0.0

cooling

(cooling) ^1,4

Derivative

"Retain.CtrlParams.

Real

100000.0 >=Td

PID derivative action

action time

Cool.Td"

>= 0.0

time for cooling

(cooling) ^1,4

Derivative

Retain.CtrlParams.

Real

TdFiltRatio>= 0.0

PID derivative delay

delay coeffi-

Cool.TdFiltRatio"

coefficient for cooling

cient (cool-

that defines the deriva-

ing) ⁴

tive lag time as a coef-

ficient from the PID

derivative time.

245

PID is easy

8.11 Commissioning the PID_Temp controller

Setting

TO-DB parameter

Data

Value range

Description

type

Proportional

"Retain.CtrlParams.

Real

1.0 >=PWeighting

Weighting of the PID

action

Cool.PWeighting"

>= 0.0

proportional gain for

weighting

cooling in either the

(cooling) ⁴

direct- or loopback-

control path.

Derivative

Retain.CtrlParams.

Real

1.0 >=DWeighting

Weighting of the PID

action

Cool.DWeighting"

>= 0.0

derivative part for cool-

weighting

ing in either the direct-

(cooling) ⁴

or loopback- control

path.

Sampling

"Retain.CtrlParams.

Real

100000.0

Internal call cycle of the

time of PID

Cool.Cycle"

>=Cycle

PID controller for cool-

algorithm

> 0.0

ing.

(cooling) ^1,4

Rounded to an integer

multiple of the FB call

cycle time.

Deadband

"Retain.CtrlParams.

Real

DeadZone>= 0.0

Width of the deadband

width (cool-

Cool.DeadZone"

for cooling control devi-

ing) ^3,4

ation

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PID is easy

8.11 Commissioning the PID_Temp controller

Setting

TO-DB parameter

Data

Value range

Description

type

Control

"Retain.CtrlParams.

Real

ControlZone> 0.0

Width of the control

Zone (cool-

Cool.ControlZone"

deviation zone for cool-

ing) ^3,4

ing where PID control is

active. If control devia-

tion leaves this range,

output is switched to

maximum output val-

ues.

Default value is

"MaxReal" so control

zone is deactivated as

long as autotuning is

not executed.

Value "0.0" is prohibit-

ed for Control Zone;

with the value "0.0",

PID_Temp behaves like

a two-position controller

that is always heating

or cooling at full power.

247

PID is easy

8.11 Commissioning the PID_Temp controller

Setting

TO-DB parameter

Data

Value range

Description

type

Controller

"PIDSelfTune.SUT.

Int

"PIDSelf-

You can select the

structure

TuneRuleCool",

Tune.SUT.

tuning algorithm for

(cooling)

TuneRuleHeat"

cooling.

"PIDSelfTune.TIR.

= 0..2,

TuneRuleCool"

Possible selections:

"PIDSelf-

• PID (Temperature)

Tune.TIR.

(=default)

TuneRuleHeat"

= 0..5

("PIDSelfTune.SUT.

TuneRuleCool" = 2)

("PIDSelfTune.TIR.

TuneRuleCool = 0)

• PID

("PIDSelfTune.SUT.

TuneRuleCool" = 0)

("PIDSelfTune.TIR.

TuneRuleCool" = 0)

• PI

("PIDSelfTune.SUT.

TuneRuleCool" = 1)

("PIDSelfTune.TIR.

TuneRuleCool" = 4)

Any other combination

shows “User defined”,

but “User defined” is

not provided by default.

“PID (Temperature)” is

new for PID_Temp,

with a specific pretun-

ing (SUT) method for

temperature processes.

Only available if you

check/select the follow-

ing items: “Activate

output (cooling)” in

“Basic settings” view

("Con-

fig.ActivateCooling" =

TRUE), and “PID pa-

rameter switchover” in

“Output settings” view

(Con-

fig.AdvancedCooling =

TRUE).

248

PID is easy

8.11 Commissioning the PID_Temp controller

Setting

TO-DB parameter

Data

Value range

Description

type

The field displays "s" (seconds) as the time units.

Only available if you check "Enable manual entry” in PID parameters ("Re-

tain.CtrlParams.SetByUser" = TRUE).

Unit of measurement is displayed at the end of the field as selected in “Basic settings” view.

Only available if you check/select the following items: "Enable manual entry” in PID parameters

("Retain.CtrlParams.SetByUser" = TRUE), “Activate output (cooling)” in “Basic settings” view

("Config.ActivateCooling" = TRUE), and “PID parameter switchover” in “Output settings” view

(Config.AdvancedCooling = TRUE).

PID start value control

You can edit the actual values of the PID configuration parameters so that the behavior of

the PID controller can be optimized in online mode.

Open the "Technology objects" for your PID controller and its "Configuration" object. To

access the start value control, click the "eyeglasses icon" in the upper left corner of the

dialog:

249

PID is easy

8.11 Commissioning the PID_Temp controller

You can now change the value of any of your PID controller configuration parameters as

shown in the figure below.

You can compare the actual value to the project (offline) start value and the PLC (online)

start value of each parameter. This is necessary to compare online/offline differences of the

Technology object data block (TO-DB) and to be informed about the values that will be used

as current values on the next Stop-to-Start transition of the PLC. In addition, a compare icon

gives a visual indication to help easily identify online/offline differences:

The figure above shows the PID parameter screen with compare icons showing which

values are different between online and offline projects. A green icon indicates that the

values are the same; a blue/orange icon indicates that the values are different.

250

Web server for easy Internet connectivity

The Web server provides Web page access to data about your CPU and to the process data

within the CPU. With these Web pages, you access the CPU (or Web-enabled CP) with the

Web browser of your PC or mobile device. The standard web pages allow authorized users

to perform these functions and more:

● Changing the operating mode (STOP and RUN) of the CPU

● Monitoring and modifying PLC tags, data block tags, and I/O values

● Viewing and downloading data logs

● Viewing the diagnostic buffer of the CPU.

● Updating the firmware of the CPU.

The Web server also allows you to create user-defined Web pages that can access CPU

data. You can develop these pages with the HTML authoring software of your choice. You

insert pre-defined "AWP" (Automation Web Programming) commands in your HTML code to

access the data in the CPU.

You set up users and privilege levels for the Web server in the device configuration for the

CPU in STEP 7.

Web browser requirement

The Web server supports the following PC Web browsers:

● Internet Explorer 8.0

● Internet Explorer 9.0

● Mozilla Firefox 17.0.1

● Google Chrome 23.0

● Apple Safari 5.1.7 (Windows)

● Apple Safari 6.0.2 (Mac)

The Web server supports the following mobile device Web browsers:

● Internet Explorer 6.0 and earlier, for HMI panels

● Mobile Safari 7534.48.3 (iOS 5.0.1)

● Mobile Android Browser 2.3.4

● Mobile Google Chrome 23.0

For browser-related restrictions that can interfere with the display of standard or user-defined

Web pages, see the topics about constraints (Page 256).

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Web server for easy Internet connectivity

9.1 Easy to use the standard Web pages

9.1

Easy to use the standard Web pages

Using the standard Web pages is easy! You only have to enable the Web server when

configuring the CPU and configure Web server users with privileges to perform the tasks

they need to do.

The Start page displays a representation of

the CPU to which you are connected and lists

general information about the CPU. If you

have Web-server enabled CPs the Start page

also displays them and allows you to connect

to Web pages through those CPs.

If you have the required privileges, you can

change the operating mode of the CPU

(STOP and RUN) or flash the LEDs.

The Variable Status page allows you to moni-

tor or modify any of the I/O or memory data in

your CPU. You must have the "read variable

status" privilege to monitor values, and the

"write variable status" privilege to modify val-

ues. You can enter a direct address (such as

I0.0), a PLC tag name, or a tag from a specific

program block. The data values automatically

refresh until you disable the automatic refresh

option.

The Diagnostic Buffer page displays the diag-

nostic buffer, and is accessible to users with

privileges to query diagnostics. You can select

the range of diagnostic entries to be dis-

played.

The diagnostic entries list the events that oc-

curred and the CPU time and date of when

the event occurred. Select the individual event

to display detailed information about that

event.

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Web server for easy Internet connectivity

9.1 Easy to use the standard Web pages

The File Browser page allows you to view,

download, or edit files in the load memory of

the CPU such as data logs (Page 122) and

recipes. Unless the CPU has Level 4 protec-

tion, all users can view the files from the File

Browser page. Users with privileges to modify

files can delete, edit and rename files.

The Module Information page in addition to

displaying information about the modules in

your station allows you to update the version

of firmware in your CPU or other modules that

support firmware update. Users with privileges

to query diagnostics can view the module

information page. Users with privileges to

perform a firmware update can update firm-

ware.

Other standard web pages display information about the CPU (such as the serial number,

the version and the article number) and about the communication parameters (such as

network addresses and physical properties of the communication interfaces).

WARNING

Unauthorized access to the CPU through the Web server

Unauthorized access to the CPU or changing PLC variables to invalid values could disrupt

process operation and could result in death, severe personal injury and/or property

damage.

Because enabling the Web server allows authorized users to perform operating mode

changes, writes to PLC data, and firmware updates, Siemens recommends that you

observe the following security practices:

• Enable access to the Web server only with the HTTPS protocol.

• Password-protect Web server user IDs with a strong password. Strong passwords are at

least ten characters in length, mix letters, numbers, and special characters, are not

words that can be found in a dictionary, and are not names or identifiers that can be

derived from personal information. Keep the password secret and change it frequently.

• Do not extend the default minimum privileges of the "Everybody" user.

• Perform error-checking and range-checking on your variables in your program logic

because Web page users can change PLC variables to invalid values.

• Use a secure Virtual Private Network (VPN) to connect to the S7-1200 PLC Web server

from a location outside your protected network.

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Web server for easy Internet connectivity

9.2 Constraints that can affect the use of the Web server

9.2

Constraints that can affect the use of the Web server

The following IT considerations can affect your use of the Web server:

● Typically, you must use the IP address of the CPU to access the standard Web pages or

user-defined Web pages, or the IP address of a wireless router with a port number. If

your Web browser does not allow connecting directly to an IP address, see your IT

administrator. If your local policies support DNS, you can connect to the IP address

through a DNS entry to that address.

● Firewalls, proxy settings, and other site-specific restrictions can also restrict access to the

CPU. See your IT administrator to resolve these issues.

● The standard Web pages use JavaScript and cookies. If your Web browser settings

disable JavaScript or cookies, enable them. If you cannot enable them, some features

are restricted. Use of JavaScript and cookies in user-defined Web pages is optional. If

used, you must enable them in your browser.

● The Web server supports Secure Sockets Layer (SSL). You can access the standard

Web pages and user-defined Web pages with an URL of either http://ww.xx.yy.zz or

https://ww.xx.yy.zz, where "ww.xx.yy.zz" represents the IP address of the CPU.

● Siemens provides a security certificate for secure access to the Web server. From the

Introduction standard Web page, you can download and import the certificate into the

Internet options of your Web browser. If you choose to not import the certificate, you will

get a security verification prompt every time you access the Web server with https://.

Number of connections

The Web server supports a maximum of 30 active HTTP connections. Various actions

consume the 30 connections, depending on the Web browser that you use and the number

of different objects per page (.css files, images, additional .html files). Some connections

persist while the Web server is displaying a page; other connections do not persist after the

initial connection.

If, for example, you are using Mozilla Firefox 8, which supports a maximum of six persistent

connections, you could use five browser or browser tab instances before the Web server

starts dropping connections. In the case where a page is not using all six connections, you

could have additional browser or browser tab instances.

Also be aware that the number of active connections can affect page performance.

Note

Log off prior to closing Web server

If you have logged in to the Web server, be sure to log off prior to closing your Web browser.

The Web server supports a maximum of seven concurrent logins.

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Web server for easy Internet connectivity

9.3 Easy to create user-defined web pages

9.3

Easy to create user-defined web pages

9.3.1

Easy to create custom "user-defined" web pages

The S7-1200 Web server also provides the means for you to create your own application-

specific HTML pages that incorporate data from the PLC. Use the HTML editor of your

choice to create these pages, and then download them to the CPU from where they are

accessible from the standard Web pages.

① HTML files with embedded AWP commands

This process involves several tasks:

● Create the HTML pages with an HTML editor

● Include AWP commands in HTML comments in the HTML code: The AWP commands

are a fixed set of commands for accessing CPU information.

● Configure STEP 7 to read and process the HTML pages.

● Generate the program blocks from the HTML pages.

● Program STEP 7 to control the use of the HTML pages.

● Compile and download the program blocks to the CPU.

● Access the user-defined Web pages from your PC or mobile device.

You can use the software package of your choice to create your own HTML pages for use

with the Web server. Be sure that your HTML code is compliant to the HTML standards of

the W3C (World Wide Web Consortium). STEP 7 does not perform any verification of your

HTML syntax.

You can use a software package that lets you design in WYSIWYG or design layout mode,

but you need to be able to edit your HTML code in pure HTML form. Most Web authoring

tools provide this type of editing; otherwise, you can always use a simple text editor to edit

the HTML code. Include the following line in your HTML page to set the charset for the page

to UTF-8:

Also be sure to save the file from the editor in UTF-8 character encoding.

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9.3 Easy to create user-defined web pages

You use STEP 7 to compile everything in your HTML pages into STEP 7 data blocks. These

data blocks consist of one control data block that directs the display of the Web pages and

one or more fragment data blocks that contain the compiled Web pages. Be aware that

extensive sets of HTML pages, particularly those with lots of images, require a significant

amount of load memory space for the fragment DBs. If the internal load memory of your CPU

is not sufficient for your user-defined Web pages, use a memory card to provide external

load memory.

To program your HTML code to use data from the S7-1200, you include AWP commands as

HTML comments. When finished, save your HTML pages to your PC and note the folder

path where you save them.

Note

The file size limit for HTML files containing AWP command is 64 kilobytes. You must keep

your file size below this limit.

Refreshing user-defined Web pages

User-defined Web pages do not automatically refresh. It is your choice whether to program

the HTML to refresh the page or not. For pages that display PLC data, refreshing periodically

keeps the data current. For HTML pages that serve as forms for data entry, refreshing can

interfere with the user entering data. If you want your entire page to automatically refresh,

you can add this line to your HTML header, where "10" is the number of seconds between

refreshes:

You can also use JavaScript or other HTML techniques to control page or data refreshing.

For this, refer to documentation on HTML and JavaScript.

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9.3 Easy to create user-defined web pages

9.3.2

Constraints specific to user-defined Web pages

The constraints for standard Web pages also apply to user-defined Web pages. In addition,

user-defined Web pages have some specific considerations.

Load memory space

Your user-defined Web pages become data blocks when you click "Generate blocks", which

require load memory space. If you have a memory card installed, you have up to the

capacity of your memory card as external load memory space for the user-defined Web

pages.

If you do not have a memory card installed, these blocks take up internal load memory

space, which is limited according to your CPU model.

You can check the amount of load memory space that is used and the amount that is

available from the Online and Diagnostic tools in STEP 7. You can also look at the properties

for the individual blocks that STEP 7 generates from your user-defined Web pages and see

the load memory consumption.

Note

If you need to reduce the space required for your user-defined Web pages, reduce your use

of images if applicable.

Quotation marks in text strings

Avoid using text strings that contain embedded single or double quotation marks in data

block tags that you use for any purpose in user-defined Web pages. Because HTML syntax

often uses single quotes or double quotes as delimiters, quotation marks within text strings

can break the display of user-defined Web pages.

For data block tags of type String that you use in user-defined Web pages, observe the

following rules:

● Do not enter single or double quotation marks in the data block tag string value in

STEP 7.

● Do not let the user program make assignments of strings containing quotes to these data

block tags.

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9.3 Easy to create user-defined web pages

9.3.3

Configuration of a user-defined Web page

To configure the user-defined Web pages, edit the "Web server" properties of the CPU.

After you enable the Web server functionality, enter the following information:

● Name and the current location of the HTML default start page to generate the DBs for the

user-defined Web pages.

● Name for your application (optional). The application name is used to further

subcategorize or group web pages. When you provide an application name, the Web

server creates an URL for your user-defined page in the following format:

http[s]://ww.xx.yy.zz/awp/<application name>/<pagename>.html

● Filename extensions of files that contain AWP commands. By default, STEP 7 analyzes

files with .htm, .html, or .js extensions. If you have additional file extensions, append

them.

● Identification numbers for the control DB number and the initial fragment DB.

After configuring the Web server, click the "Generate blocks" button to generate the DBs

from the HTML pages. After you generate the DBs, your Web pages are a part of your user

program. The control data block for the operation of your Web pages, and the "fragment"

DBs contain all of the HTML pages.

9.3.4

Using the WWW instruction

The WWW instruction allows your user-defined Web pages to be accessible from the

standard Web pages. Your user program only has to execute the WWW instruction once to

enable access to the user-defined Web pages. You might, however, choose to make the

user-defined Web pages available only under certain circumstances. Your user program

could then call the WWW instruction according to your application requirements.

Table 9- 1

WWW instruction

LAD / FBD

SCL

Description

ret_val := #WWW(

Identifies the control DB to be used for the user-

defined Web pages.

ctrl_db:=_uint_in_);

The control data block is the input parameter to

the WWW instruction and specifies the content of

the pages as represented in the fragment data

blocks, as well as state and control information.

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9.3 Easy to create user-defined web pages

Your user program typically uses the control DB directly as created by the "Generate blocks"

process, with no additional manipulation. However, the user program can set global

commands in the control DB to deactivate the web server, or to subsequently reactivate it.

Also, for user-defined pages that you create as manual fragment DBs, the user program

must control the behavior of these pages through a request table in the control DB, as

described in the S7-1200 Programmable Controller System Manual.

261

Motion control is easy

The CPU provides motion control functionality for the operation of stepper motors and servo

motors with pulse interface. The motion control functionality takes over the control and

monitoring of the drives.

●

The "Axis" technology object configures the mechanical drive data, drive interface,

dynamic parameters, and other drive properties.

●

You configure the pulse and direction outputs of the CPU for controlling the drive.

●

Your user program uses the motion control instructions to control the axis and to initiate

motion tasks.

●

Use the PROFINET interface to establish the online connection between the CPU and the

programming device. In addition to the online functions of the CPU, additional

commissioning and diagnostic functions are available for motion control.

Note

Changes that you make to the motion control configuration and download in RUN mode

do not take effect until the CPU transitions from STOP to RUN mode.

① PROFINET

② Pulse and direction outputs

③ Power section for stepper motor

④ Power section for servo motor

The DC/DC/DC variants of the CPU S7-1200 have onboard

outputs for direct control of drives. The relay variants of the

CPU require the signal board with DC outputs for drive con-

trol.

A signal board (SB) expands the onboard I/O to include a few additional I/O points. An SB

with two digital outputs can be used as pulse and direction outputs to control one motor. An

SB with four digital outputs can be used as pulse and direction outputs to control two motors.

Built-in relay outputs cannot be used as pulse outputs to control motors. Whether you use

onboard I/O or SB I/O or a combination of both, you can have a maximum number of four

pulse generators.

263

Motion control is easy

The four pulse generators have default I/O assignments; however, they can be configured to

any digital output on the CPU or SB. Pulse generators on the CPU cannot be assigned to

SMs or to distributed I/O.

Note

Pulse-train outputs cannot be used by other instructions in the user program

When you configure the outputs of the CPU or signal board as pulse generators (for use with

the PWM or motion control instructions), the corresponding output addresses no longer

control the outputs. If your user program writes a value to an output used as a pulse

generator, the CPU does not write that value to the physical output.

Table 10- 1 Maximum number of controllable drives

Type of CPU

Onboard I/O;

With an SB

No SB installed

(2 x DC outputs)

(4 x DC outputs)

With direc-

Without

With direc-

Without

With direc-

Without

tion

direction

tion

direction

tion

direction

CPU 1211C

DC/DC/DC

AC/DC/RLY

DC/DC/RLY

CPU 1212C

DC/DC/DC

AC/DC/RLY

DC/DC/RLY

CPU 1214C

DC/DC/DC

AC/DC/RLY

DC/DC/RLY

CPU 1215C

DC/DC/DC

AC/DC/RLY

DC/DC/RLY

CPU 1217C

DC/DC/DC

Note

The maximum number of pulse generators is four.

Whether you use onboard I/O, SB I/O, or a combination of both, you can have a maximum

number of four pulse generators.

264

Motion control is easy

Table 10- 2 CPU output: maximum frequency

CPU

CPU output channel

Pulse and direction

A/B, quadrature, up/down,

output

and pulse/direction

1211C

Qa.0 to Qa.3

100 kHz

1212C

Qa.0 to Qa.3

100 kHz

Qa.4, Qa.5

20 kHz

1214C and 1215C

Qa.0 to Qa.3

100kHz

Qa.4 to Qb.1

20 kHz

1217C

DQa.0 to DQa.3

1 MHz

(.0+, .0- to .3+, .3-)

DQa.4 to DQb.1

100 kHz

Table 10- 3 SB signal board output: maximum frequency (optional board)

SB signal board

SB output channel

Pulse and direction

A/B, quadrature, up/down,

output

and pulse/direction

SB 1222, 200 kHz

DQe.0 to DQe.3

200kHz

200 kHz

SB 1223, 200 kHz

DQe.0, DQe.1

200kHz

200 kHz

SB 1223

DQe.0, DQe.1

20 kHz

Table 10- 4 Limit frequencies of pulse outputs

Pulse output

Frequency

Onboard

4 PTO: 2 Hz ≤ f ≤ 1 MHz, 4 PTO: 2 Hz ≤ f ≤ 100 kHz, or any combination of

these values for 4 PTOs.^{1 2}

Standard SB

2 Hz ≤ f ≤ 20 kHz

High-speed SBs

2 Hz ≤ f ≤ 200 kHz

See the table below for four possible CPU 1217C output speed combinations.

See the table below for four possible CPU 1211C, CPU 1212C, CPU 1214C, or CPU 1215C output speed combinations.

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Motion control is easy

Example: CPU 1217C pulse output speed configurations

Note

The CPU 1217C can generate pulse outputs up to 1 MHz, using the onboard differential

outputs.

The examples below show four possible output speed combinations:

● Example 1: 4 - 1 MHz PTOs, no direction output

● Example 2: 1 - 1 MHz, 2 - 100 kHz, and 1 - 20 kHz PTOs, all with direction output

● Example 3: 4 - 200 kHz PTOs, no direction output

● Example 4: 2 - 100 kHz PTOs and 2 - 200 kHz PTOs, all with direction output

P = Pulse

CPU on-board outputs

High-speed SB outputs

Standard

SB out-

D = Direction

puts

1 MHz Outputs (Q)

100 kHz Outputs (Q)

200 kHz Outputs (Q)

20 kHz

Outputs

(Q)

0.0+

0.1+

0.2+

0.3+

0.4

0.5

0.6

0.7

1.0

1.1

4.0

4.1

4.2

4.3

4.0

4.1

0.0-

0.1-

0.2-

0.3-

Ex. 1:

PTO1

4 - 1

PTO2

MHz

PTO3

(no

direction

PTO4

output)

Ex. 2: 1 -

PTO1

1 MHz; 2

PTO2

- 100

PTO3

and 1 -

20 kHz

PTO4

(all with

direction

output)

Ex. 3:

PTO1

4 - 200

PTO2

kHz (no

PTO3

direction

output)

PTO4

Ex. 4:

PTO1

2 - 100

PTO2

kHz;

PTO3

2 - 200

kHz (all

PTO4

with

direction

output)

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Motion control is easy

Example: CPU 1211C, CPU 1212C, CPU 1214C, and CPU 1215C pulse output speed configurations

The examples below show four possible output speed combinations:

● Example 1: 4 - 100 kHz PTOs, no direction output

● Example 2: 2 - 100 kHz PTOs and 2 - 20 kHz PTOs, all with direction output

● Example 3: 4 - 200 kHz PTOs, no direction output

● Example 4: 2 - 100 kHz PTOs and 2 - 200 kHz PTOs, all with direction output

P = Pulse

CPU on-board outputs

High-speed SB outputs

Low-speed

SB outputs

D = Direction

100 kHz Outputs (Q)

20 kHz Outputs (Q)

200 kHz Outputs (Q)

20 kHz

Outputs

(Q)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

1.0

1.1

4.0

4.1

4.2

4.3

4.0

4.1

CPU 1211C

CPU 1212C

CPU

1212C

CPU 1214C

CPU

CPU 1214C

1214C

CPU 1215C

CPU

CPU 1215C

1215C

Ex. 1:

PTO1

4 - 100

PTO2

kHz (no

PTO3

direction

output)

PTO4

Ex. 2:

PTO1

2 - 100

PTO2

kHz;

PTO3

2 - 20

kHz (all

PTO4

with direc-

tion out-

put)

Ex. 3:

PTO1

4 - 200

PTO2

kHz (no

PTO3

direction

output)

PTO4

Ex. 4:

PTO1

2 - 100

PTO2

kHz;

PTO3

2 - 200

kHz (all

PTO4

with direc-

tion out-

put)

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Motion control is easy

10.1 Phasing

10.1

Phasing

You have four options for the "Phasing" interface to the stepper/servo drive. These options

are as follows:

● PTO (pulse A and direction B): If you select a PTO (pulse A and direction B) option, then

one output (P0) controls the pulsing and one output (P1) controls the direction. P1 is high

(active) if pulsing is in the positive direction. P1 is low (inactive) if pulsing is in the

negative direction:

● PTO (count up A and count down B): If you select a PTO (count up A and count down B)

option, then one output (P0) pulses for positive directions and a different output (P1)

pulses for negative directions:

● PTO (A/B phase-shifted): If you select a PTO (A/B phase-shifted) option, then both

outputs pulse at the speed specified, but 90 degrees out-of-phase. It is a 1X

configuration, meaning one pulse is the amount of time between positive transitions of

P0. In this case, the direction is determined by which output transitions high first. P0

leads P1 for the positive direction. P1 leads P0 for the negative direction.

The number of pulses generated is based upon the number of 0 to 1 transitions of Phase

A. The phase relationship determines the direction of movement:

PTO (A/B phase-shifted)

Phase A leads phase B (positive movement)

Phase A lags phase B (negative movement)

Number of pulses

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Motion control is easy

10.1 Phasing

● PTO (A/B phase-shifted - fourfold): If you select a PTO (A/B phase-shifted - fourfold)

option, then both outputs pulse at the speed specified, but 90 degrees out-of-phase. The

fourfold is a 4X configuration, meaning one pulse is the transition of each output (both

positive and negative). In this case, the direction is determined by which output

transitions high first. P0 leads P1 for the positive direction. P1 leads P0 for the negative

direction.

Fourfold is based upon positive and negative transitions of both Phase A and Phase B.

You configure the number of transitions. The phase relationship (A leading B or B leading

A) determines the direction of movement.

PTO (A/B phase-shifted - fourfold)

Phase A leads phase B (positive movement)

Phase A lags phase B (negative movement)

Number of pulses

● PTO (pulse and direction (direction de-selected)): If you de-select the direction output in a

PTO (pulse and direction (direction de-selected)), then output (P0) controls the pulsing.

Output P1 is not used and is available for other program uses. Only positive motion

commands are accepted by the CPU in this mode. Motion control restricts you from

making illegal negative configurations when you select this mode. You can save an

output if your motion application is in one direction only. Single phase (one output) is

shown in the figure below (assuming positive polarity):

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Motion control is easy

10.2 Configuring a pulse generator

10.2

Configuring a pulse generator

Add a Technology object:

- In the Project tree, expand the node "Technology Objects" and select "Add new

object".

- Select the "Axis" icon (rename if required) and click "OK" to open the configuration

editor for the axis object.

- Display the "Select PTO for Axis Control" properties under the "Basic parameters" and

select the desired pulse.

Note

If the PTO has not been previously configured in the CPU Properties, the PTO is

configured to use one of the onboard outputs.

If you use an output signal board, then select the "Device configuration" button to go

to the CPU Properties. Under "Parameter assignment", in the "Pulse options",

configure the output source to a signal board output.

- Configure the remaining Basic and Extended parameters.

Program your application: Insert the MC_Power instruction in a code block.

- For the Axis input, select the axis technology object that you created and configured.

- Setting the Enable input to TRUE allows the other motion instructions to function.

- Setting the Enable input FALSE cancels the other motion instructions.

Note

Include only one MC_Power instruction per axis.

Insert the other motion instructions to produce the required motion.

Note

Configuring a pulse generator to signal board outputs: Select the "Pulse generators

(PTO/PWM)" properties for a CPU (in Device configuration) and enable a pulse generator.

Two pulse generators are available for each S7-1200 CPU V1.0, V2.0, V2.1, and V2.2.

S7-1200 CPU V3.0 and V4.0 CPUs have four pulse generators available. In this same

configuration area under "Pulse options", select Pulse generator used as: "PTO".

Note

The CPU calculates motion tasks in "slices" or segments of 10 ms. As one slice is being

executed, the next slice is waiting in the queue to be executed. If you interrupt the motion

task on an axis (by executing another new motion task for that axis), the new motion task

may not be executed for a maximum of 20 ms (the remainder of the current slice plus the

queued slice).

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Motion control is easy

10.3 Open loop motion control

10.3

Open loop motion control

10.3.1

Configuring the axis

You connect the open loop axis on the PLC and the drive through a PTO (Pulse Train

Output).

STEP 7 provides the configuration tools, the commissioning tools, and the diagnostic tools

for the "Axis" technology object.

① Drive

④ Commissioning

② Technology object

⑤ Diagnostics

③ Configuration

Note

For CPU firmware releases V2.2 and earlier, the PTO requires the internal functionality of a

high-speed counter (HSC). This means the corresponding HSC cannot be used elsewhere.

The assignment between PTO and HSC is fixed. If PTO1 is activated, it will be connected to

HSC1. If PTO2 is activated, it will be connected to HSC2. You cannot monitor the current

value (for example, in ID1000) when pulses are occurring.

S7-1200 V3.0 and later CPUs do not have this restriction; all HSCs remain available for

program use when pulse outputs are configured in these CPUs.

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Motion control is easy

10.3 Open loop motion control

Table 10- 5 STEP 7 tools for motion control

Tool

Description

Configuration

Configures the following properties of the "Axis" technology object:

• Selection of the PTO to be used and configuration of the drive interface

• Properties of the mechanics and the transmission ratio of the drive (or machine or system)

• Properties for position limits, dynamics, and homing

Save the configuration in the data block of the technology object.

Commissioning

Tests the function of your axis without having to create a user program. When the tool is started,

the control panel will be displayed. The following commands are available on the control panel:

• Enable and disable axis

• Move axis in jog mode

• Position axis in absolute and relative terms

• Home axis

• Acknowledge errors

The velocity and the acceleration / deceleration can be specified for the motion commands. The

control panel also shows the current axis status.

Diagnostics

Monitors of the current status and error information for the axis and drive.

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Motion control is easy

10.3 Open loop motion control

The tree selector for the PTO axis does not include

the Encoder, Modulo, Position monitoring, and

Control loop configuration menus.

After you create the technology object for the axis,

you configure the axis by defining the basic pa-

rameters, such as the PTO and the configuration of

the drive interface. You also configure the other

properties of the axis, such as position limits, dy-

namics, and homing.

Note

You may have to adapt the values of the input parameters of motion control instructions to

the new dimension unit in the user program.

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Motion control is easy

10.3 Open loop motion control

Configure the properties for the drive signals, drive

mechanics, and position monitoring (hardware and

software limit switches).

You configure the motion dynamics and the behav-

ior of the emergency stop command.

You also configure the homing behavior (passive and active).

Use the "Commissioning" control panel to test the functionality independently from your user

program.

Click the "Startup" icon to commission the axis.

The control panel shows the current status of the axis. Not only can you enable and disable

the axis, but you can also test the positioning of the axis (both in absolute and relative terms)

and can specify the velocity, acceleration and deceleration. You can also test the homing

and jogging tasks. The control panel also allows you to acknowledge errors.

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Motion control is easy

10.3 Open loop motion control

10.3.2

Commissioning

"Status and error bits" diagnostic function

Use the "Status and error bits" diagnostic function to monitor the most important status and

error messages for the axis. The diagnostic function display is available in online mode in

"Manual control" mode and in "Automatic control" when the axis is active.

Table 10- 6 Status of the axis

Status

Description

Enabled

The axis is enabled and ready to be controlled via motion control tasks.

(Tag of technology object: <Axis name>.StatusBits.Enable)

Homed

The axis is homed and is capable of executing absolute positioning tasks of motion control instruc-

tion "MC_MoveAbsolute". The axis does not have to be homed for relative homing. Special situa-

tions:

• During active homing, the status is FALSE.

• If a homed axis undergoes passive homing, the status is set to TRUE during passive homing.

(Tag of technology object: <Axis name>.StatusBits.HomingDone)

Error

An error has occurred in the "Axis" technology object. More information about the error is available

in automatic control at the ErrorID and ErrorInfo parameters of the motion control instructions. In

manual mode, the "Last error" field of the control panel displays detailed information about the

cause of error.

(Tag of technology object: <Axis name>.StatusBits.Error)

Control panel active

The "Manual control" mode was enabled in the control panel. The control panel has control priority

over the "Axis" technology object. The axis cannot be controlled from the user program.

(Tag of technology object: <Axis name>.StatusBits.ControlPanelActive)

Table 10- 7 Drive status

Status

Description

Drive ready

The drive is ready for operation.

(Tag of technology object: <Axis name>.StatusBits.DriveReady)

Error

The drive has reported an error after failure of its ready signal.

(Tag of technology object: <Axis name>.ErrorBits.DriveFault)

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Motion control is easy

10.3 Open loop motion control

Table 10- 8 Status of the axis motion

Status

Description

Standstill

The axis is at a standstill.

(Tag of technology object: <Axis name>.StatusBits.StandStill)

Accelerating

The axis accelerates.

(Tag of technology object: <Axis name>.StatusBits.Acceleration)

Constant velocity

The axis travels at constant velocity.

(Tag of technology object: <Axis name>.StatusBits.ConstantVelocity)

Decelerating

The axis decelerates (slows down).

(Tag of technology object: <Axis name>.StatusBits.Deceleration)

Table 10- 9 Status of the motion mode

Status

Description

Positioning

The axis executes a positioning task of motion control instruction "MC_MoveAbsolute" or

"MC_MoveRelative" or of the control panel.

(Tag of technology object: <Axis name>.StatusBits.PositioningCommand)

Speed Command

The axis executes a task at set speed of motion control instruction "MC_MoveVelocity" or

"MC_MoveJog" or of the control panel.

(Tag of technology object: <Axis name>.StatusBits.SpeedCommand)

Homing

The axis executes a homing task of motion control instruction "MC_Home" or the control

panel.

(Tag of technology object: <Axis name>.StatusBits.Homing)

Table 10- 10 Error bits

Error

Description

Min software limit reached

The lower software limit switch has been reached.

(Tag of technology object: <Axis name>.ErrorBits.SwLimitMinReached)

Min software limit exceeded

The lower software limit switch has been exceeded.

(Tag of technology object: <Axis name>.ErrorBits.SwLimitMinExceeded)

Max software limit reached

The upper software limit switch has been reached.

(Tag of technology object: <Axis name>.ErrorBits.SwLimitMaxReached)

Max software limit exceeded

The upper software limit switch has been exceeded.

(Tag of technology object: <Axis name>.ErrorBits.SwLimitMaxExceeded)

Negative hardware limit

The lower hardware limit switch has been approached.

(Tag of technology object: <Axis name>.ErrorBits.HwLimitMin)

Positive hardware limit

The upper hardware limit switch has been approached.

(Tag of technology object: <Axis name>.ErrorBits.HwLimitMax)

PTO already used

A second axis is using the same PTO and is enabled with "MC_Power".

(Tag of technology object: <Axis name>.ErrorBits.HwUsed)

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Motion control is easy

10.3 Open loop motion control

Error

Description

Configuration error

The "Axis" technology object was incorrectly configured or editable configuration data

were modified incorrectly during runtime of the user program.

(Tag of technology object: <Axis name>.ErrorBits.ConfigFault)

General Error

An internal error has occurred.

(Tag of technology object: <Axis name>.ErrorBits.SystemFault)

"Motion status" diagnostic function

Use the "Motion status" diagnostic function to monitor the motion status of the axis. The

diagnostic function display is available in online mode in "Manual control" mode and in

"Automatic control" when the axis is active.

Table 10- 11 Motion status

Status

Description

Target position

The "Target position" field indicates the current target position of an active positioning task of

motion control instruction "MC_MoveAbsolute" or "MC_MoveRelative" or of the control panel.

The value of the "Target position" is only valid during execution of a positioning task.

(Tag of technology object: <Axis name>.MotionStatus.TargetPosition)

Current position

The "Current position" field indicates the current axis position. If the axis is not homed, the

value indicates the position value relative to the enable position of the axis.

(Tag of technology object: <Axis name>.MotionStatus.Position)

Current velocity

The "Current velocity" field indicates the actual axis velocity.

(Tag of technology object: <Axis name>.MotionStatus.Velocity)

Table 10- 12 Dynamic limits

Dynamic limit

Description

Velocity

The "Velocity" field indicates the configured maximum velocity of the axis.

(Tag of technology object: <Axis name>.Config.DynamicLimits.MaxVelocity)

Acceleration

The "Acceleration" field indicates the currently configured acceleration of the axis.

(Tag of technology object: <Axis name>.Config.DynamicDefaults.Acceleration)

Deceleration

The "Deceleration" field indicates the currently configured deceleration of the axis.

(Tag of technology object: <Axis name>.Config.DynamicDefaults.Deceleration)

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Motion control is easy

10.3 Open loop motion control

Motion start value control

You can edit the actual values of the Motion configuration parameters so that the behavior of

the process can be optimized in online mode.

Open the "Technology objects" for your motion control and its "Configuration" object. To

access the start value control, click the "eyeglasses icon" in the upper left corner of the

dialog:

You can now change the value of any of your motion control configuration parameters as

shown in the figure below.

You can compare the actual value to the project (offline) start value and the PLC (online)

start value of each parameter. This is necessary to compare online/offline differences of the

Technology object data block (TO-DB) and to be informed about the values that will be used

as current values on the next Stop-to-Start transition of the PLC. In addition, a compare icon

gives a visual indication to help easily identify online/offline differences.

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Motion control is easy

10.4 Closed loop motion control

10.4

Closed loop motion control

10.4.1

Configuring the axis

You connect the closed loop axis on the PLC and the drive through the analog drive or

PROFIdrive. The closed loop axis requires an encoder as well.

STEP 7 provides the configuration tools, the commissioning tools, and the diagnostic tools

for the "Axis" technology object.

① Drive

④ Commissioning

② Technology object

⑤ Diagnostics

③ Configuration

Table 10- 13 STEP 7 tools for closed loop motion control

Tool

Description

Configuration

Configures the following properties of the "Axis" technology object:

• Selection of the analog drive connection or PROFIdrive to be used and configuration of the

drive and encoder interface

• Properties of the mechanics and the transmission ratio of the drive and encoder (or machine

or system)

• Properties for position limits, dynamics, and homing

Save the configuration in the data block of the technology object.

Commissioning

Tests the function of your axis without having to create a user program. When the tool is started,

the control panel will be displayed. The following commands are available on the control panel:

• Enable and disable axis

• Move axis in jog mode

• Position axis in absolute and relative terms

• Home axis

• Acknowledge errors

The velocity and the acceleration / deceleration can be specified for the motion commands. The

control panel also shows the current axis status.

Diagnostics

Monitors of the current status and error information for the axis and drive.

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Motion control is easy

10.4 Closed loop motion control

Note

You may have to adapt the values of the input parameters of motion control instructions to

the new dimension unit in the user program.

After you create the technology object for the axis, you configure the axis by defining the

basic parameters, either the Analog drive or the PROFIdrive connection and the

configuration of the drive and encoder.

The tree selector for the analog drive or

PROFIdrive connection includes the Encoder,

Modulo, Position monitoring, and Control loop con-

figuration menus.

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Motion control is easy

10.4 Closed loop motion control

Analog drive connection configuration

In the General configuration dialog, you select the

following parameters:

• "Analog drive connection" radio button

• Unit of measurement

In the Drive configuration dialog, you select the

following parameters:

• Analog drive hardware outputs

• Data exchange drive velocities

In the Encoder configuration dialog, you select the

following parameters:

• Analog drive encoder coupling (for example, a

high-speed counter (HSC))

• HSC interface

• Encoder type

• Fine resolution

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Motion control is easy

10.4 Closed loop motion control

PROFIdrive configuration

In the General configuration dialog, you select the

following parameters:

• "PROFIdrive" radio button

• Unit of measurement

In the Drive configuration dialog, you select the

following parameters:

• PROFIdrive drive

• Data exchange with the drive

In the Encoder configuration dialog, you select the

following parameters:

• PROFIdrive encoder coupling (for example, a

PROFIdrive encoder on PROFINET)

• PROFIdrive encoder

• Data exchange with the encoder

• Encoder type

• Fine resolution

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Motion control is easy

10.4 Closed loop motion control

Extended parameters

You can also configure the following properties of the closed loop axis:

● Modulo

● Position limits

● Dynamics

● Homing

● Position monitoring

● Following error

● Standstill signal

● Control loop

Modulo: You can configure a "Modulo" axis to

move the load in a cyclic area which has a start

value/start position and a given length. If the posi-

tion of the load reaches the end of this area, it is

automatically set to the start value again. You ena-

ble the "Length" and "Modulo start value" fields

when you check the "Enable Modulo" check box.

Position limits: You can configure the properties for

the drive signals, drive mechanics, and position

monitoring (hardware and software limit switches).

Dynamics: You can configure the motion dynamics

and the behavior of the emergency stop command.

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Motion control is easy

10.4 Closed loop motion control

Homing: You can configure the homing behavior (passive and active).

"Positioning monitoring": You can configure

tolerance time as well as minimum dwell

time for the positioning window.

The system connects the following three

parameters directly with the axis TO-DB:

• Positioning window

• Tolerance time

• Minimum dwell time in positioning window

"Following error": You can configure the

difference of the allowed error distance over

a velocity range. You check the "Enable

following error monitoring" check box to acti-

vate following error. You can configure the

following the parameters:

• Maximum following error

• Following error

• Start dynamic adjustment

• Maximum velocity

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Motion control is easy

10.4 Closed loop motion control

"Standstill signal": You can configure the

following the parameters:

• Minimum dwell time in standstill window

• Standstill window.

"Control loop": You can configure the veloci-

ty gain known as "Precontrol (Kv factor)".

Use the "Commissioning" control panel to test the functionality independently from your user

program.

Click the "Startup" icon to commission the axis.

The control panel shows the current status of the axis. Not only can you enable and disable

the axis, but you can also test the positioning of the axis (both in absolute and relative terms)

and can specify the velocity, acceleration and deceleration. You can also test the homing

and jogging tasks. The control panel also allows you to acknowledge errors.

286

Motion control is easy

10.4 Closed loop motion control

10.4.2

Commissioning

"Status and error bits" diagnostic function

Use the "Status and error bits" diagnostic function to monitor the most important status and

error messages for the axis. The diagnostic function display is available in online mode in

"Manual control" mode and in "Automatic control" when the axis is active.

Table 10- 14 Status of the axis

Status

Description

Enabled

The axis is enabled and ready to be controlled via motion control tasks.

(Tag of technology object: <Axis name>.StatusBits.Enable)

Homed

The axis is homed and is capable of executing absolute positioning tasks of motion control instruc-

tion "MC_MoveAbsolute". The axis does not have to be homed for relative homing. Special situa-

tions:

• During active homing, the status is FALSE.

• If a homed axis undergoes passive homing, the status is set to TRUE during passive homing.

(Tag of technology object: <Axis name>.StatusBits.HomingDone)

Error

An error has occurred in the "Axis" technology object. More information about the error is available

in automatic control at the ErrorID and ErrorInfo parameters of the motion control instructions. In

manual mode, the "Last error" field of the control panel displays detailed information about the

cause of error.

(Tag of technology object: <Axis name>.StatusBits.Error)

Control panel active

The "Manual control" mode was enabled in the control panel. The control panel has control priority

over the "Axis" technology object. The axis cannot be controlled from the user program.

(Tag of technology object: <Axis name>.StatusBits.ControlPanelActive)

Table 10- 15 Drive status

Status

Description

Drive ready

The drive is ready for operation.

(Tag of technology object: <Axis name>.StatusBits.DriveReady)

Error

The drive has reported an error after failure of its ready signal.

(Tag of technology object: <Axis name>.ErrorBits.DriveFault)

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10.4 Closed loop motion control

Table 10- 16 Status of the axis motion

Status

Description

Standstill

The axis is at a standstill.

(Tag of technology object: <Axis name>.StatusBits.StandStill)

Accelerating

The axis accelerates.

(Tag of technology object: <Axis name>.StatusBits.Acceleration)

Constant velocity

The axis travels at constant velocity.

(Tag of technology object: <Axis name>.StatusBits.ConstantVelocity)

Decelerating

The axis decelerates (slows down).

(Tag of technology object: <Axis name>.StatusBits.Deceleration)

Table 10- 17 Status of the motion mode

Status

Description

Positioning

The axis executes a positioning task of motion control instruction "MC_MoveAbsolute" or

"MC_MoveRelative" or of the control panel.

(Tag of technology object: <Axis name>.StatusBits.PositioningCommand)

Speed Command

The axis executes a task at set speed of motion control instruction "MC_MoveVelocity" or

"MC_MoveJog" or of the control panel.

(Tag of technology object: <Axis name>.StatusBits.SpeedCommand)

Homing

The axis executes a homing task of motion control instruction "MC_Home" or the control

panel.

(Tag of technology object: <Axis name>.StatusBits.Homing)

Table 10- 18 Error bits

Error

Description

Min software limit reached

The lower software limit switch has been reached.

(Tag of technology object: <Axis name>.ErrorBits.SwLimitMinReached)

Min software limit exceeded

The lower software limit switch has been exceeded.

(Tag of technology object: <Axis name>.ErrorBits.SwLimitMinExceeded)

Max software limit reached

The upper software limit switch has been reached.

(Tag of technology object: <Axis name>.ErrorBits.SwLimitMaxReached)

Max software limit exceeded

The upper software limit switch has been exceeded.

(Tag of technology object: <Axis name>.ErrorBits.SwLimitMaxExceeded)

Negative hardware limit

The lower hardware limit switch has been approached.

(Tag of technology object: <Axis name>.ErrorBits.HwLimitMin)

Positive hardware limit

The upper hardware limit switch has been approached.

(Tag of technology object: <Axis name>.ErrorBits.HwLimitMax)

PTO already used

A second axis is using the same PTO and is enabled with "MC_Power".

(Tag of technology object: <Axis name>.ErrorBits.HwUsed)

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10.4 Closed loop motion control

Error

Description

Configuration error

The "Axis" technology object was incorrectly configured or editable configuration data

were modified incorrectly during runtime of the user program.

(Tag of technology object: <Axis name>.ErrorBits.ConfigFault)

General Error

An internal error has occurred.

(Tag of technology object: <Axis name>.ErrorBits.SystemFault)

"Motion status" diagnostic function

Use the "Motion status" diagnostic function to monitor the motion status of the axis. The

diagnostic function display is available in online mode in "Manual control" mode and in

"Automatic control" when the axis is active.

Table 10- 19 Motion status

Status

Description

Target position

The "Target position" field indicates the current target position of an active positioning task of

motion control instruction "MC_MoveAbsolute" or "MC_MoveRelative" or of the control panel.

The value of the "Target position" is only valid during execution of a positioning task.

(Tag of technology object: <Axis name>.MotionStatus.TargetPosition)

Current position

The "Current position" field indicates the current axis position. If the axis is not homed, the

value indicates the position value relative to the enable position of the axis.

(Tag of technology object: <Axis name>.MotionStatus.Position)

Current velocity

The "Current velocity" field indicates the actual axis velocity.

(Tag of technology object: <Axis name>.MotionStatus.Velocity)

Table 10- 20 Dynamic limits

Dynamic limit

Description

Velocity

The "Velocity" field indicates the configured maximum velocity of the axis.

(Tag of technology object: <Axis name>.Config.DynamicLimits.MaxVelocity)

Acceleration

The "Acceleration" field indicates the currently configured acceleration of the axis.

(Tag of technology object: <Axis name>.Config.DynamicDefaults.Acceleration)

Deceleration

The "Deceleration" field indicates the currently configured deceleration of the axis.

(Tag of technology object: <Axis name>.Config.DynamicDefaults.Deceleration)

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10.4 Closed loop motion control

You can now change the value of any of your motion control configuration parameters as

shown in the figure below.

You can compare the actual value to the project (offline) start value and the PLC (online)

start value of each parameter. This is necessary to compare online/offline differences of the

Technology object data block (TO-DB) and to be informed about the values that will be used

as current values on the next Stop-to-Start transition of the PLC. In addition, a compare icon

gives a visual indication to help easily identify online/offline differences.

The figure above shows the Motion parameter screen with compare icons showing which

values are different between online and offline projects. A green icon indicates that the

values are the same; a blue/orange icon indicates that the values are different.

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10.5 Configuring the TO_CommandTable_PTO

10.5

Configuring the TO_CommandTable_PTO

You can configure a MC_CommandTable instruction using the Technology objects. The

following example demonstrates how this is done.

Adding a Technology object

1. In the Project tree, expand the node "Technology Objects" and select "Add new object".

2. Select the "CommandTable" icon (rename if required), and click "OK" to open the

configuration editor for the CommandTable object.

Planning the steps for your application

You can create the desired movement sequence in the "Command Table" configuration

window, and check the result against the graphic view in the trend diagram.

You can select the command types that are to be used for processing the command table.

Up to 32 steps can be entered. The commands are processed in sequence, easily producing

a complex motion profile.

Table 10- 21 MC_CommandTable command types

Command type

Description

Empty

The empty serves as a placeholder for any commands to be added. The

empty entry is ignored when the command table is processed

Halt

Pause axis.

Note: The command only takes place after a "Velocity setpoint" command.

Positioning Relative

Positions the axis based upon distance. The command moves the axis by

the given distance and velocity.

Positioning Absolute

Positions the axis based upon location. The command moves the axis to

the given location, using the velocity specified.

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10.5 Configuring the TO_CommandTable_PTO

Command type

Description

Velocity setpoint

Moves the axis at the given velocity.

Wait

Waits until the given period is over. "Wait" does not stop an active travers-

ing motion.

Separator

Adds a "Separator" line above the selected line. The separator line allows

more than one profile to be defined in a single command table.

In the figure below, "Command complete" is used as the transition to the next step. This type

of transition allows your device to decelerate to the start/stop speed and then accelerate

once again at the start of the next step.

① Axis decelerates to the start/stop speed between steps.

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10.5 Configuring the TO_CommandTable_PTO

In the figure below, "Blending motion" is used as the transition to the next step. This type of

transition allows your device to maintain its velocity into the start of the next step, resulting in

a smooth transition for the device from one step to the next. Using blending can shorten the

total time required for a profile to execute completely. Without blending, this example takes

seven seconds to run. With blending, the execution time is reduced by one second to a total

of six seconds.

① Axis continues to move and accelerates or decelerates to the next step velocity, saving time and

mechanical wear.

The operation of your CommandTable is controlled by an MC_CommandTable instruction,

as shown below:

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10.6 Operation of motion control for S7-1200

10.6

Operation of motion control for S7-1200

10.6.1

CPU outputs used for motion control

The CPU provides four pulse output generators. Each pulse output generator provides one

pulse output and one direction output for controlling a stepper motor drive or a servo motor

drive with pulse interface. The pulse output provides the drive with the pulses required for

motor motion. The direction output controls the travel direction of the drive.

The PTO output generates a square wave output of variable frequency. Pulse generation is

controlled by configuration and execution information supplied through H/W configuration

and/or SFCs/SFBs.

Based upon the user’s selection while the CPU is in RUN mode, either the values stored in

the image register or the pulse generator outputs drive the digital outputs. In STOP mode,

the PTO generator does not control the outputs.

Onboard CPU outputs and outputs of a signal board can be used as pulse and direction

outputs. You select between onboard CPU outputs and outputs of the signal board during

device configuration under Pulse generators (PTO/PWM) on the "Properties" tab. Only PTO

(Pulse Train Output) applies to motion control.

The table below shows the default I/O assignments; however, the four pulse generators can

be configured to any digital output.

Note

Pulse-train outputs cannot be used by other instructions in the user program.

When you configure the outputs of the CPU or signal board as pulse generators (for use with

the PWM or motion control instructions), the corresponding output addresses no longer

control the outputs. If your user program writes a value to an output used as a pulse

generator, the CPU does not write that value to the physical output.

Note

PTO direction outputs can be freed for use elsewhere in your program.

Each PTO requires the assignment of two outputs: one as a pulse output and one as a

direction output. You can use just the pulse output and not the direction output. You can then

free the direction output for other purposes in your user program. The output cannot be used

for both the PTO direction output and in the user program, simultaneously.

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10.6 Operation of motion control for S7-1200

Table 10- 22 Default address assignments of the pulse and direction outputs

Usage of outputs for motion control

Pulse

Direction

PTO1

Built-in I/O

Q0.0

Q0.1

SB I/O

Q4.0

Q4.1

PTO2

Built-in I/O

Q0.2

Q0.3

SB I/O

Q4.2¹

Q4.3¹

PTO3

Built-in I/O

Q0.4 ²

Q0.5²

SB I/O

Q4.0

Q4.1

PTO4

Built-in I/O

Q0.6 ³

Q0.7 ³

SB I/O

Q4.2

Q4.3

Outputs Q4.2 and Q4.3 are only available on the SB1222 DQ4.

The CPU 1211C does not have outputs Q0.4, Q0.5, Q0.6, or Q0.7. Therefore, these outputs can-

not be used in the CPU 1211C.

The CPU 1212C does not have outputs Q0.6 or Q0.7. Therefore, these outputs cannot be used in

the CPU 1212C.

This table applies to the CPU 1211C, CPU 1212C, CPU 1214C, CPU 1215C, and CPU 1217C

PTO functions.

Drive interface

For motion control, you can optionally configure a drive interface for "Drive enabled" and

"Drive ready". When using the drive interface, the digital output for the drive enable and the

digital input for "drive ready" can be freely selected.

Note

The firmware will take control through the corresponding pulse and direction outputs if the

PTO (Pulse Train Output) has been selected and assigned to an axis.

With this takeover of the control function, the connection between the process image and I/O

output is also disconnected. While the user has the possibility of writing the process image of

pulse and direction outputs via the user program or watch table, this is never transferred to

the I/O output. Accordingly, it is also not possible to monitor the I/O output via the user

program or watch table. The information read merely reflects the value of the process image

and does not match the actual status of the I/O output in any respect.

For all other CPU outputs that are not used permanently by the CPU firmware, the status of

the I/O output can be controlled or monitored via the process image, as usual.

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10.6 Operation of motion control for S7-1200

10.6.2

Hardware and software limit switches for motion control

Use the hardware and software limit switches to limit the "allowed travel range" and the

"working range" of your axis.

① Mechanical stop

A Allowed travel range for the axis

② Lower and upper hardware limits

B Working range of the axis

③ Lower and upper software limits

C Distance

Hardware and software limit switches must be activated prior to use in the configuration or in

the user program. Software limit switches are only active after homing the axis.

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10.6 Operation of motion control for S7-1200

Hardware limit switches

Hardware limit switches determine the maximum travel range of the axis. Hardware limit

switches are physical switching elements that must be connected to interrupt-capable inputs

of the CPU. Use only hardware limit switches that remain permanently switched after being

approached. This switching status may only be revoked after a return to the allowed travel

range.

Table 10- 23 Available inputs for hardware limits

Description

RPS

LIM-

LIM+

Built-in I/O

I0.0 - I1.5

SB I/O

I4.0 - I4.3

When the hardware limit switches are approached, the axis brakes to a standstill at the

configured emergency deceleration. The specified emergency deceleration must be

sufficient to reliably stop the axis before the mechanical stop. The following diagram

presents the behavior of the axis after it approaches the hardware limit switches.

① The axis brakes to a standstill at the configured emergency deceleration.

② Range in which the hardware limit switches signal the stats "approached".

[Velocity]

Allowed travel range

C Distance

D Mechanical stop

Lower hardware limit switch

Upper hardware limit switch

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10.6 Operation of motion control for S7-1200

WARNING

Risks with changes to filter time for digital input channel

If the filter time for a digital input channel is changed from a previous setting, a new "0"

level input value may need to be presented for up to 20.0 ms accumulated duration before

the filter becomes fully responsive to new inputs. During this time, short "0" pulse events of

duration less than 20.0 ms may not be detected or counted.

This changing of filter times can result in unexpected machine or process operation, which

may cause death or serious injury to personnel, and/or damage to equipment.

To ensure that a new filter time goes immediately into effect, a power cycle of the CPU

must be applied.

Software limit switches

Software limit switches limit the "working range" of the axis. They should fall inside the

hardware limit switches relative to the travel range. Because the positions of the software

limit switches can be set flexibly, the working range of the axis can be restricted on an

individual basis depending on the current traversing profile. In contrast to hardware limit

switches, software limit switches are implemented exclusively by means of the software and

do not require their own switching elements.

If software limit switches are activated, an active motion is stopped at the position of the

software limit switch. The axis is braked at the configured deceleration. The following

diagram presents the behavior of the axis until it reaches the software limit switches.

① The axis brakes to a standstill at the configured deceleration.

[Velocity]

Working range

C Distance

D Lower software limit switch

Upper software limit switch

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10.6 Operation of motion control for S7-1200

Use additional hardware limit switches if a mechanical endstop is located after the software

limit switches and there is a risk of mechanical damage.

Additional information

Your user program can override the hardware or software position limits by enabling or

disabling both hardware and software limits functionality. The selection is made from the

Axis DB.

● To enable or disable the hardware limit functionality, access the "Active" tag (Bool) in the

DB path "<axis name>/Config/PositonLimits_HW". The state of the "Active" tag enables

or disables the use of hardware position limits.

● To enable or disable software position limit functionality, access "Active" tag (Bool) in the

DB path "<axis name>/Config/Position Limits_SW". The state of this "Active" tag enables

or disables the software position limits.

You can also modify the software position limits with your user program (for example, to add

flexibility for machine setup or to shorten machine change-over time). Your user program can

write new values to the " MinPosition " and " MaxPosition " tags (engineering units in Real

format) in the DB "<axis name>/Config/PositionLimits_SW".

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10.6 Operation of motion control for S7-1200

10.6.3

Homing

10.6.3.1

Homing the axis

Homing refers to the matching of the axis coordinates to the real, physical drive position. (If

the drive is currently at position x, the axis will be adjusted to be in position x.) For position-

controlled axes, the entries and displays for the position refer exactly to these axis

coordinates.

Note

The agreement between the axis coordinates and the real situation is extremely important.

This step is necessary to ensure that the absolute target position of the axis is also achieved

exactly with the drive.

The MC_Home instruction initiates the homing of the axis.

There are 4 different homing functions. The first two functions allow the user to set the

current position of the axis and the second two position the axis with respect to a Home

reference Sensor.

●

Mode 0 - Direct Referencing Absolute: When executed this mode tells the axis exactly

where it is. It sets the internal position variable to the value of the Position input of the

Homing instruction. This is used for machine calibration and setup.

The axis position is set regardless of the reference point switch. Active traversing motions

are not aborted. The value of the Position input parameter of the MC_Home instruction is

set immediately as the reference point of the axis. To assign the reference point to an

exact mechanical position, the axis must be at a standstill at this position at the time of

the homing operation.

●

Mode 1 - Direct Referencing Relative: When executed this mode uses the internal

position variable and adds the value of the Position input on the Homing instruction to it.

This is typically used to account for machine offset.

The axis position is set regardless of the reference point switch. Active traversing motions

are not aborted. The following statement applies to the axis position after homing: New

axis position = current axis position + value of the Position parameter of the MC_Home

instruction.

●

Mode 2 - Passive Referencing: When the axis is moving and passes the Reference Point

Switch the current position is set as the home position. This feature will help account for

normal machine wear and gear backlash and prevent the need for manual compensation

for wear. The Position input on the Homing instruction, as before, adds to the location

indicated by the Reference Point Switch allowing easy offset of the Home position.

During passive homing, the MC_Home instruction does not carry out any homing motion.

The traversing motion required for this step must be implemented by the user via other

motion control instructions. When the reference point switch is detected, the axis is

homed according to the configuration. Active traversing motions are not aborted upon

start of passive homing.

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