I place RX+,RX-,TX+,TX- connections on the RS-4xx connector of my board. I also placed GND with 100ohm resistance to my board's GND.
But there is no GND connection on my RS232-RS4xx converter's terminal block. Only RX+/- and TX+/- exists...
In MAX485 part of my schematic, I added biasing resistors, terminating resistors , terminating jumper and unidirectional protection diodes...
If the PC and my board powered from different power supplies in the building, will this cause a problem?