TTL to RS485 tranceiver faulty outputs

Using Arduino Networking, Protocols, and Devices
1

hi! first post here, noob alert!
i'm trying to create make two boards (NodeMCU and arduino mega) communicate serially over an rs485 setup
((using two of these converters https://core-electronics.com.au/ttl-uart-to-rs485-converter-module.html))

when i test each board alone with the laptop's serial monitor and usb cable, all is working fine and both can normally send and receive serial messages like "a" or "b" telling a potentiometer's input range.

when i connect the two boards via the rs485 converters ((nodemcu tx/rx >> 1st converter's RO/DI , then A/B lines between converters, then 2nd converter to arduino mega tx3/rx3 ))
i only get -1 or 241 on the arduino mega (receiver side))) ((only this amount of details mentioned to explain the idea, but of course there are triggers for send/receive mode and so on))

i guessed maybe i'm using the converters incorrectly.
so,
i mapped the converter's functionality with logic inputs without a microcontroller, and it's outputs (RO/DI) and always logic high (, no matter what (send or receive mode, high or low input)

that seems wrong, how is it supposed to send messages to the arduino mega if the two RO/DI ports are always giving the tx3/rx3 logic high ?

2

i mapped the converter's functionality with logic inputs without a microcontroller, and it's outputs (RO/DI) and always logic high (, no matter what (send or receive mode, high or low input)

Using the linked modules the RO pins are pulled high, so that state is correct for your setup. The same applies for the DI pins to have a defined state even if the MCU is tri-state.

If your transfer failed for some reason, I guess it's either a wrong wiring (you failed to provide the wiring diagram as the sticky post at the top of the forum requested you to do) or an error in the programming but as you also failed to post your sketches, we cannot help you further.