Some modbus tcp slaves require slave id

[tskjot]

Some Modbus TCP slaves seem to require the setting of the modbus unit id in the modbus tcp packets, even though this should not be necessary. To ensure maximal interoperability, I suggest adding the unitid paramter to the methods in ModbusTCPMaster.java as in the following example:

  public synchronized BitVector readCoils(int unitid, int ref, int count)
      throws ModbusException {
    m_ReadCoilsRequest.setUnitID(unitid);
    m_ReadCoilsRequest.setReference(ref);
    m_ReadCoilsRequest.setBitCount(count);
    m_Transaction.setRequest(m_ReadCoilsRequest);
    m_Transaction.execute();
    BitVector bv = ((ReadCoilsResponse) m_Transaction.getResponse()).getCoils();
    bv.forceSize(count);
    return bv;
  }

[Steve]

This has been incorporated in v2.0 - available soon

[Dan Salt]

Same goes for the ModbusCoupler. It has a unit_id field (private), but no way to set it via the API. I'm converting from Jamod to j2mod (so many improvements -- great work), and that method (setUnitId()) is one that's missing in the refactored code.

Thanks,
Dan

[Steve]

Check out the v2.0 - this is a junit tested scenario so you should find it works fine now.