TRB245/RS485 debug?

[magnusgrey]

I have a TRB245 and I can’t get RS485 to work with a one-phase meter.
Tested ok with other RS485 master so meter is ok:

From test reading one register, I get in TRB245:

“Request failed, result: communication error: Response not from requested slave.”

Is there a way to debug the TRB245?
I would like to trace what is being sent and what is being received.

[Vilius.G]

Greetings, magnusgrey,

Thank you for your message,

It looks like the TRB245 is having trouble communicating with your meter, even though the meter works with another RS‑485 master. This usually points to configuration or wiring issues rather than a faulty meter. Here’s what to do:

1. Check physical layer

• Confirm RS‑485 lines (A/B) aren’t reversed.
• Add 120 Ω termination resistors at each end of the bus if the cable is long.

2. Verify serial settings

• Match baud rate, parity, stop bits, and flow control between the TRB245 and the meter.

3. Confirm protocol / addressing

• Ensure the TRB245 is set to communicate with the correct device address or ID.
• If the meter expects Modbus RTU, check that TRB245 is using the same function codes and register addresses. If a custom protocol is used, ensure the TRB245 matches it.

4. Test communication from TRB245

• If you have ssh access, you can use ubus or equivalent tools to send a test request and observe the response.
• Optionally, use a PC + RS‑485 adapter to sniff traffic and verify what the TRB245 is sending and receiving.

5. Firmware & support check

• I recommend using the latest firmware available for the TRB245.

The error “Response not from requested slave” usually means the TRB245 isn’t getting the response it expects — often due to wiring, slave ID mismatch, or timing issues.

I hope this helps!

Kind regards,
V.