I'm trying to establish a full-duplex and then a half duplex communication and need to wire a device output to an RS485/422 to RS232 converter.
Here is the device output pins for full and half duplex modes:
And here is the RS485/422 to RS232 converter screw pins(DATA+ DATA- are for RS485 rest TXs and RXs are for RS422 manual says):
I have 3 questions here.
1-) Is my wiring below from the converter to the device correct for full-duplex?
RS422(FULL DUPLEX)
TX+ <—–> RXD+
TX- <—–> RXD-
RX+ <—–> TXD+
RX- <—–> TXD-
2-) Here is most confusion at half-duplex wiring. Converter shows D for RS485, device shows another notation such as TXD. Here I don't get why they use TXD-/RXD- format for half-duplex. Why both shown?
Anyway is my wiring below from the converter to the device correct for half-duplex?
RS485(HALF DUPLEX)
D1+ <—–> TXD+
D1- <—–> TXD-
3-) And finally can I use the half-duplex mode with RS422 full-duplex wiring without wiring back for RS485?
Best Answer
1) Yes this is correct.
2) In half duplex, rx and tx data streams both share the same pair of wires so you have rx/tx+ and rx/tx-, otherwise known simply as + and -, or B and A (or confusingly some manufacturers call them A and B). So your wiring as shown is correct.
3) On many devices you can simply loop the rx+,tx+ terminals together and rx-,tx- terminals together for half duplex mode (RS485), but the device must support this.