Hello,
From all the information the most likely scenario is RS232 cabling/communication being an issue. The primary reason why that could be an issue is because you've mentioned the entire scheme working with your TRB145 as well as RS485 cabling. Could you please let me know which pins are used when connecting devices with RS485?
Also, just to be absolutely sure - do both the TRB142 and the consumer device have female RS232 connectors?
Additionally, I would like to ask you a question regarding the relay - I believe you've mentioned it's not an external one, so if I understand correctly, you want to use the TRB142 as a digital relay?
Best regards,
Tomas.