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Entry type: FAQ Entry ID: 88359827, Entry date: 03/26/2014
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Getting Started of ET200S 1 STEP Module

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Getting Started of ET200S 1 STEP Module
Getting Started of ET200S 1 STEP 5V/204KHz

1. Module introduction

1.1 Overview
ET200S 1STEP module outputs pulses to control stepper motor drive, the number of output pulses decide the movement distance of stepper motor, and the output pulse frequency decides the speed of stepper motor.
Module Order Number: 6ES7138-4DC00-0AB0

1.2 Module characteristics


Fig. 1: 1STEP step module

  • 1 channel, which may be used to control 1 stepper motor
  • reference point switch digital input
  • external stop or external pulse enable digital input
  • The pulse and direction signals are in RS422 level differential output mode.
  • Max. output frequency: 204kHZ
  • Max. number of output pulses: 1048575
  • 4 LED status indicators
  • 2 Operating modes: search-for-reference-point mode and incremental mode

2. Module wiring


Fig. 2: 1STEP terminal wiring diagram

  • Terminal 1 and 5: pulse signal differential output
  • Terminal 4 and 8: direction signal differential output
  • Terminal 2 and 3: external stop or external pulse enable digital input ID (see chapter 4.2 for function selection)
  • Terminal 6 and 7: reference point switch digital input

3. Hardware configuration
The step module 1STEP may be used after being installed after ET200S interface module or ET200S CPU module.
In this document, IM151-7 CPU module is taken as an example.


Table 1: Software and hardware configuration


Fig. 3: Configuration diagram of ET200S station

4. Hardware configuration and parameter configuration

4.1 Hardware configuration
1) Complete ET200S station installation and wiring according to Fig. 2 and Fig. 3
2) Open STEP7, create a new project in the manager, and then insert a S7-300 station
3) Enter hardware configuration interface to configure. Select IM151-7 CPU to drag it directly into the station configuration window.


Fig. 4: Insert IM151-7 CPU

4) Insert power supply module PM-E DC24 and step module 1STEP into No.4 and No.5 slots respectively.


Fig. 5: Hardware configuration

4.2 Module parameter configuration


Fig. 6: Parameter interface of 1STEP module

4.2.1 Module parameter configuration specification
1) Group Diagnostic: group diagnosis
2) Base Frequency: basic frequency, in Hz, marked as Fb
3) Multiplier n: multiplication factor n, value range 1-255. This multiplication factor decides start/stop frequency Fss, and the calculating formula is: Fss=Fb×n
4) Time i: time factor i, value range 1-255. This time factor decides acceleration and deceleration a, in Hz/ms, and the calculating formula is: a = Fb ×R / (i×0.128 ms)
5) Function DI: digital value DI input function selection, which may be configured as external pulse enable input or external cease fire input. The default is external pulse enable input.
6) External Stop, Limit Stop: external stop, limit stop signal type. Break contact is normally closed signal, and make contact is normally seen signal. The default is normally closed signal access.

4.2.2 Parameters adopted in example in this document
The parameter configuration for the example in this document is shown in Fig. 6.
1) not activate group diagnosis
2) basic frequency 4Hz
3) multiplication factor 1, start/stop frequency 4Hz
4) time factor 1, acceleration/ deceleration 31.25 Hz/ms
5) external pulse enable input
6) external stop input and limit input signals in normally closed type

5. Programming

5.1 Module input/output address assignment
Similar to other ET200S function blocks, the step module 1STEP also controls and accesses the module by reading and writing I/O address directly.
Feedback signal (input), occupying 8 bytes. See Table 2 for input address assignment.
Control signal (output), occupying 8 bytes. See Table 3 for output address assignment.
The detailed input and output address assignment variables are seen in ET200S position control operation manual. Refer to the link below:
/cs/document/9260790?caller=view&lc=en-WW


Table 2: Input address assignment


Table 3: Output address assignment

5.2 Program of project example
To facilitate reading and writing of the bit, byte and word in address of this module, use MOVE command in the ladder programming environment to send input address area PIB272-PIB279 to MB10-MB17 and send MB20-MB27 to PQB272-PQB279. Reading/writing access to 1STEP module is completed through MB address area.
See Fig. 5 for 1STEP module IO address assignment.


Fig. 7: Program of project example

6. Mode description and example

6.1 Search-for-reference-point mode
Synchronize the axis by executing search-for-reference-point mode, viz. create the matching relationship between mechanical zero point and electrical zero point.

6.1.1 Search-for-reference-point mode description
Mode=1
The reference point switch is in normally open signal access mode.
Search for reference point output frequency Fss and Fa.
Fss starts up stop frequency. See chapter 4.2.1 for related descriptions.
Fa output frequency: Fa = Fb ×G × R
Fb: basic frequency. Configure it in 1STEP module parameters. See chapter 4.2.1 for related descriptions.
Multiplier G: multiplication factor G. Value range: 1-255, module output address byte: 0. Refer to Table 3.
Reduction Factor R:Reduction factor R. The 7th bit in module output address byte 4. Refer to Table 3. Module output address 4.7=0, R=1. Module output address 4.7=0, R=0.1.


Fig. 8: Search for reference point

6.1.2 Example of search-for-reference-point mode
The example in this document is in the mode shown in Fig. 8, viz. search for reference in CW direction.

  1. Write output control variable through Variable table:
     
    Fig. 9: Reference point mode control variable

    1) M24.0=1 search-for-reference-point Mode = 1
    2) M25.0=1, M25.1=1: as the limit switch signal in former module parameter configuration is in normally closed input mode, there shall be signal input before the software limit switch is activated. Refer to chapter 4.2.2.
    3) M25.2=0: not activating software pulse enable signal. As DI has been enabled as external pulse enable signal input in the former module parameter configuration, internal software pulse enable signal will not be used at this moment. Refer to chapter 4.2.2.
    4) Set M24.2, then reset M24.4 (falling edge signal is valid), and start up search-for-reference-point mode. The pulse output frequency is Fa.
    5) MB20=1, M24.7=0: multiplication factor G = 1, reduction factor R = 1, and Fa frequency value is
    Fa = Fb ×G × R=4Hz×1×1=4Hz。
     
  2. Read input status variable through Variable table:

    Fig. 10: Reference point mode status variable

    1) M15.2=1: activating external pulse enable signal
    2) M15.0 = 1: drive enable
    3) After search-for-reference point is started up, the task at M14.0=1 position is activated, and the operation at M15.7=1 position is executed. Wait for reference point switching signal M15.1.
    4) M15.1=1: the reference point signal arrives, and search for reference point is completed. M14.4=1, synchronization operation completes, M14.2=1, arrive at the position, M15.3=1, search for reference point stops.  

6.2 Incremental mode
The incremental mode is the main operation mode of 1STEP. This operation mode may control the stepper motor to move to a given distance at the given speed.

6.2.1 Description of incremental mode
Mode=0
The number of output pulses decides the movement distance of stepper motor, and the maximum number of pulses is 1048575.
The output pulse frequency determines the speed of stepper motor.
Output frequency in incremental mode: Fss, Fa
The direction signal is used as start signal.

Notes: the actual displacement corresponding to pulse number and the actual speed corresponding to pulse frequency are determined by stepper motor drive, which are not set in 1STEP module.

6.2.2 Example of incremental mode

  1. Write output control variable through Variable table:

    Fig. 11: Control variable in incremental mode

    1) M24.0=0 incremental mode = 0
    2) M25.0=1、M25.1=1: as the limit switch signal in former module parameter configuration is in normally closed input mode, there shall be signal input before the software limit switch is activated. Refer to chapter 4.2.2.
    3) MB20=1, M24.7=0: multiplication factor G = 1, reduction factor R = 1, and the output frequency Fa is
    Fa = Fb ×G × R=4Hz×1×1=4Hz.
    4) Number of ouput pulses: making up 20-bit address through MB21-23 that is used to store pulse number, whose max. value is 0xFFFFF=1048575
    Number of MB21 ouput pulses (bit 16 to bit 19)
    Number of MB22 ouput pulses (bit 8 to bit 15)
    Number of MB23 ouput pulses (bit 0 to bit 7)
    Bit 20 to bit 23 of MB21 are not used.
    In this example, the assignment value is 0 x 100, viz. 256 pulses.
    5) Set M24.4, then reset M24.4 (falling edge signal is valid), and start up incremental mode and move in CW direction.
  2. Read input status variable through Variable table:

    Fig. 12: Status variable in incremental mode

    1) After incremental mode is started up, the task at M14.0=1 position is activated, and the operation at M15.7=1 position is executed.
    2) MD10 displays the number of remaining pulses. In Fig. 12, 220 pulses have not been sent.
    3) MD10=0: complete pulse send, clear M14.0 and M15.7, and arrive at M14.2=1 position. Incremental mode output completes.

This document introduces step module ET200S 1STEP and its basic operations. For more information about operation method, diagnosis method and technical parameters, etc. of this module, please refer to manual "ET 200S Position Operating Instructions". This manual may be downloaded through the following link:
/cs/document/9260790?caller=view&lc=en-WW

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