We've recently tried to use the DTM Browser to communicate with a ModbusTCP device which has data available for reading on register 30001 upward, and data for writing to at 40001 and upward. I would have expected this to be a common situation, where the DTM Browser Generic ModbusTCP Device would be suitable, however on investigation, the ModbusTCP DTM Browser Generic Device is only able to access 40001 Holding Registers.
Has anyone come across the same issue?
Was there a workaround found (which didn't involve the use of DATA_EXCH / READ_VAR)?
Solved! Go to Solution.
As far as I know IO-scanning (DTM browser) only allows for reading/writing 4XXXX (%MWxxx) registers, meaning only the Modbus function codes 3, 16 and 23 are supported.
Other Modbus function codes, reading/writing 0xxxx, 1xxxx and 3xxxx are supported by function blocks only.