Arduino opta and WaveShare Modbus RTU 32-Ch Relay Module

Hi everyone,

I'm struggling with RS485 Modbus RTU communication between Arduino Opta RS485 and Waveshare Modbus RTU Relay (16/32CH).

Does anyone have experience with this combination? Any advice or known working configs?

Wiring:
Opta A- → Waveshare B-
Opta B+ → Waveshare A+
GND → GND

A+ <-> GND:2.095V, B <-> GND:1.755V