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    Does any one have experience communicating to a Schneider Electric MDrive stepper motor via ASCII. I am using a BRX sending ASCII strings to the drive. I finally got the out going commands to be received and most of them are correct. I can not get the drive to send back data with the PR(print) command. I'm using the Streamout command and from the success bit turning on the Stream in command.
    Any help would be GREAT.

    Thanks


  • #2
    Does the data coming back use CR/LF at the end for end-of-response delimiter? Or is the response always a specific fixed size?

    One thing to utilize in your STREAMOUT instruction is that since the BRX is the MASTER, you should CHECK the "Flush INPUT Device first" because the BRX PLC will buffer up these response packets, but you need to FLUSH the PLC's INPUT buffer every time you STREAMOUT to ensure there's no "left overs" from an old unprocessed response.
    There are 10 kinds of people in this world, those who know binary, and those who do not.

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    • #3
      The MDrive does require a CR at the end of any string to it and I believe it sends a CR at the end of the string coming out of the MDrive. Since I have wrote this I have most of the reads working. By Reads I mean STREAMOUT "pr aCR". This is print the Acceleration with a CR at the end. The big issue now is returning the current position of the motor. "pr pCR". It returns the current position then the motor runs off as if I gave it a MOVE RELATIVE command. very odd. Schneider Electric did not have any good answers for me, at least the guy I talked to... Yes the "Flush INPUT Device first" was very important. I am looking for the CR to end the STREAMIN command. One of my biggest issues for the non-communicating was having the - to - and + to + wires crossed. Needs to be + to - and - to +. Then things started to work.

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      • #4
        Originally posted by GJameson65 View Post
        One of my biggest issues for the non-communicating was having the - to - and + to + wires crossed. Needs to be + to - and - to +. Then things started to work.
        RS485 should normally be - to - and + to +, but the definition of - and + is not as uniform as you might hope and not everyone labels them the same way.

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        • #5
          Thanks guys. I think I'm OK for now. I think it is between the Schneider guys and me now.

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