TRB245 - Error Reading RS485 Sensor

NETWORKING SOLUTIONS
1

Hello,

I am trying to read the data of an RS485 sensor and forward it to an MQTT server via the TRB245.

The following is my current setup and no matter what I do all I get is “Failed to test request, check your configuration” when testing to read the sensor data.

If I understand correctly the RS485A will be connected to D+ and RS485B to D-

Green is A, White is B
The sensor is working correctly when I use an RS485 to USB adapter, I get the correct readings using Modbus Poll on my PC.

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Appreciate any help.

3

Hello,

The proper wiring for the Modbus RS485 communication between server (sensor) and client (TRB) should look like it’s shown in the image below:

TRB2XX_RS485_2wire
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Additionally, please check the similar topic that might bring some insights here:

Let me know if this helps.

Best regards,

4

Hello Martynas

I updated the wiring and the issue is still the same.

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I did take a look into that topic and I already did what he suggested but I had no luck in getting it to work.

5

Hello @ravensborn,

Could you confirm a few additional points?

  1. Are the wiring poles correct? If not known, try switching them and ensure 2X8 pin connector is screwed properly and tight.
  2. Is the correct Data type (according to the sensor’s documentation) selected? Also, ensure that other necessary parameters are chosen as the right ones.

Furthermore, if you have a USB to RS485 adapter, for testing purposes, I’d suggest simulating serial Modbus communication, according to the wiki configuration example article available here: Simulate Modbus serial communication RutOS - Teltonika Networks Wiki

Kind regards,