I am having serial communication problems. What is the problem?

There may be a few different causes to this issue. Check each item below:

  • RS-485/RS-232: Check that your system is configured for the right type of serial communication.
    • PC Control: In most cases, a converter will be necessary for RS-485 communication.
    • PLC Control: Many PLCs have RS-485 or RS-232 communication built in.
  • Serial Port Configuration: Check that the settings below match with your PC/PLC.
    • Baud Rate: Make sure to match with the device.
    • Byte Size: 8 bits
    • Parity: None
    • Flow Control: None
    • Stop Bit: 1
  • Device Address: Check that the commands that are being sent are pre-pended with the correct device address. Check product manual for details.
  • RS-485 Wirings:
    • Termination: For an RS-485 network, it may be required that a 120 Ohm resistor is placed at the beginning and end of the bus. Note that on short communication buses, or buses with a small number of nodes, termination resistors may not be needed.
    • Twisted Pair Wiring: To reduce noise, it is recommended to use twisted pair wiring for the 485+ and 485- lines.
    • Daisy chaining: For a multi-drop RS-485 network, be sure that the network uses daisy-chain wiring.
    • Number of Nodes: The maximum number of nodes recommended is 32. Increasing beyond this number will require special attention.


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    Keith Mungal

    How do I check the Baud Rate for the Motor Controller ?

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