RS232 GND pin

[rtatibouet]

Hello,
I own an Axon S215.
I want to use the RS232 interface with a 12V RFID reader.
How should I use the "GND" pin for RS232 on the Axon ? Do I need to use it ?

I use another reader (12V as well) with the RS485 interface, but this one has no "GND" pin.

Thanks !

[Martin Kudláček]

Hello @rtatibouet,
the RS485 and RS232 are completely different buses.

The RS485 is differential and doesn't need the GND, since the logic levels are based on the voltage difference between A and B terminal

The RS232 is not differential and the TX / RX logic levels are based on the voltages between TX and GND and RX and GND.

Best regards,
Martin