TRB255 RS485/Modbus 2 Wire-network wiring

[Duncan]

I have a TRB255 and an Modbus energy meter with “A” and “B” Modbus terminals.

TRB255 RS485 - Teltonika Networks Wiki - I haven’t been able to make sense of this.

On the TRB255 there is R+, R- and D+ and D-. How do I connect the two?

[Marija]

Hello,

In reference to the example provided on the wiki page for configuring a 2-wire RS485 network, here’s how you can set it up on the TRB255 device:

1. Identify the Signal Wires:
   • R+ and R- are the signal wires for RS485 communication.
   • D+ and D- are the data lines.
2. Connect D+ to R+:
   • Connect the wire labeled as D+ to the terminal labeled as R+.
3. Connect D- to R-:
   • Connect the wire labeled as D- to the terminal labeled as R-.
4. Termination Resistors:
   • Place a termination resistor of 120 Ω between R+ and R- at each end of the cable. This means you’ll have one termination resistor at the device end and another at the other end of the cable.

This configuration ensures proper communication on the RS485. If you have any further questions, feel free to ask!

Best Regards,