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S300 - operation mode change

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dear guys,

I am writing to you about technical support in the way of changing operation mode in the S343 drive unit with homing subroutine.

I am using two S343 to power up 2 linear axes with interpolation. I control them with an PLC control board which has RS422 step/dir(or pulse/dir) outputs which are connected to X5 terminal(pic. below) via double shielded separately grounded cable with ferrite rings at both sides.


AGND from red ellipse I have connected to common 0V potential/ground/GND/PE.

Drives are in external gearing mode OPMODE4 all time long but in one moment I need to swap control mode to motion task OPMODE8 and after back to external gearing mode OPMODE4. Basically it is for more precise finding of machine 0 reference. 

I have a homing routine controlled by the PLC control board but the home reference sensor is not as precise as I need. In this way I wanted to add an extra homing feature which is possible in the driver unit S3xx. Homing powered by digital input and finding 0 pulse of motor mounted encoder.  This procedure subroutine really improves machine goals and reduces time of setting up the device.

I made the connection of drivers as you can see below in .pdf or in the schematic. 


The Driver has connected all digital inputs. PSTOP/NSTOP standard NC PNP sensors.

I add in DriveGUI interface declarations of DI1 which I want to use for swap the OPMODE(defined A and B mode as I need to use) and DI2 which I want to use for starting subroutine of motion task/homing and in homing section I choose homing in 1 revolution and 0 pulse of encoder(in my way resolver here). If I have no motion task, there it is 0 motion task which is homing subroutine if I am not wrong.

Here the real problem is staring. Probing subroutine made in PLC ladder.

  1. I made this setting. 
  2. I did eeprom saving subroutine with driver restart. 
  3. I turned on the device in OPMODE 4[low level of DI1]
  4. It did referencing in the software layer of control. Device hitted reference and it moved away back in 3 turns of servo.
  5. It turned OFF the external hardware enable of the drive.
  6. delay 500ms  
  7. It turned ON DI1(which changes OPMODE from 4[low level of DI1] to 8[high level of DI1]. 
  8. delay 500ms
  9. tI turned ON the external hardware enable of the drive.
  10. delay 500ms  
  11. It turned ON DI2(which started the homing subroutine//,0pulse in 1rev).
  12. delay 50ms
  13. It turned OFF DI2(which started the homing subroutine//,0pulse in 1rev).  
  14. delay 5000ms(wait for reference with some extra time)
    • (in the future I want to add feedback from the drive, when is the motion task of homing done...)
  15. It turned OFF the external hardware enable of the drive.  
  16. It turned OFF DI1(which changes mode from 8[high level of DI1] to 4[low level of DI1]. 
  17. delay 500ms
  18. It turned ON the external hardware enable of the drive. OPMODE 4[low level of DI1]

After the first of this subroutine servo started moving very fast in a random direction and it hitted the limit. I did know what happened there. But I found, there are damaged high speed RS422 receivers in the control unit. But how? It works fine and there was no problem at all till the new subroutine. 

What I found about receivers, there are high speed chips which are very - VERY sensitive to voltage drops above -,5VDC or peaks higher then 7VDC. (

Is there any possibility, in OPMODE 8, due the restart of the driver or in operation mode changing subroutine, that there are at X5 terminals some higher voltage as I described? above 7VDC or are the terminal pins of X5 grounded direct? I burned out high speed control unit ports for generating step/dir signals. 

I replaced DS26C31TM chips at the output of the PLC control unit. I have a nice differential RS422 signal from STEP/DIR outputs before I connected to drivers. 

I think there should be a short circuit but how? I need to avoid the next ugly mistake.

I am using S343 fw.3.89 in hw rev. 03.01 + AKM42E with 2 pole resolver. 

Can you write me the right steps of homing/referencing subroutine with S300 drive in my case please?

I think I can add relay interuption of wires at X5(pulse/dir) connector in OPMODE4 which they will be interuped due homing subroutine of OPMODE8? Is it possible by this hack to avoid my trouble please?

Sincerely Ladislav


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