I’m trying communication from a RS232C communication module (DT300-31) to a recorder using DAQ32 software, but *E0401 Communication error* is displayed and communication fails.

On the RS232C communication module, set communication parameters by using the dip switches on the front of the module. Make sure the communication module’s dip switches match what is displayed on the DAQ32's “Environment, diagnosis, and calibration” screen. Also, after changing the dip switch settings, restart the recorder. Also check the cable wiring and COM port numbers.