Need help configuring both devices.

[h25r]

Hi!
I explain my setup
ECU: Speeduino runing on DIY efi core v1. Receives/sends some info via serial from an external stm32 to cluster and vss signal(pazi88 m52tu pnp)

GPIO with dxcontrol. Mega2560 with A0 pin receiving data from the sensor i want to datalog.

Im unable to connect both. I tried crossing tx rx, changing addresses, etc etc
If i cross tx and rx, ecu-dashboard serial connection crash
If i connect tx with tx and rx with rx, same thing.

Its possible have 3 devices on the serial 3 line?
I attach screenshots from the config, can someone tell me if i have addresses ok?