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Stepper motor not responding to ascii out...

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  • Stepper motor not responding to ascii out...

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ID:	126361 I am using a P1K plc to try and create an FP move using a stepper motor (AMP 4023-828) and STP-DRV-4850 drive. I am able to operate the motor when setting up the drive parameters with the PC but when I try to do it with the P1K program I am getting no response. I am new to this and am probably making a rookie mistake and any help would be sincerely appreciated. My drive parameters are: Mode: Step and Direction, Baud: 9600, EN Input: General Purpose, Output: General Purpose. I am using the RS-232 port on the P1K and it is configured as follows: Security: Read/Write, Protocol: Ascii/Custom Protocol, Baud: 9600, Parity: None, Data Bits: 8, Stop Bits: 1, RTS Mode: Assert During Transmit. I am trying to leverage on the SCL program in the help files focusing specifically on the FP section ( I made a copy and took out what I thought I did not need). Attached are pics of the program during monitor mode and I did assure that the RS-232 LED'S on the PLC were illuminated which I believe means that things are indeed being transmitted to the drive. If necessary I can also upload the program itself and thank you in advance for your time

  • #2
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ID:	126363 This is the end of the FP move...


    • #3
      Did you just use a random RJ12 cable you had around? Or did you buy this one specifically:

      I looked up the datasheets for the P1k CPU and the stepper drive to find the RS-232 pinouts:

      And it looks like you need a cable that will swap wires between pins 1 and 2, and 4 and 5 on the different cable ends to make the TX/RX match up. The cable I linked above does that:

      A regular phone cord that uses the same RJ12 connectors are usually "straight through" meaning pins connect to the same number pin on the other end and there is no swapping, or "reverse" which just has the pins swapped the oposite on the other end.. So they wont work in many modbus serial comm situations. For your situation you need the pins swapped in a very specific way to make the transmit and receive match up.
      Last edited by MikeN; 11-04-2019, 09:41 AM.


      • #4
        Yes, I did in fact grab the first RJ12 cable I had laying around and while talking to our IT person he had mentioned that the cord was "straight through". Thank you so much for making me aware of making sure that any time I am going to attempt serial communication to make sure that the pin outs on each component match up as well as providing me the cable print and drive/cpu comm port layouts. Have a great day!