I have a custom-designed circuit that communicates to and from the external world through an RS422 interface. I wish to communicate with it with an Arduino, preferably UNO. The RS422, much like the RS485, uses two lines for both the receive and transmit lines (one positive, one negative). From what I can find on the net, RS422 uses 0-5V digital communication, which is the same as the Arduino serial pins, right?
Can I use one of the lines, the positive (?), for both the TX and RX of the RS422 interface and connect them to pins 0 and 1 of the Arduino? Or would I have to connect to the USB plug of the Arduino?
The problem I'm facing is I already have a custom-designed Arduino shield that sends and received serial data, and I completely forgot about the RS422 interface. I can easily sort out the multiple devices on one UART bus in software, but I wasn't sure whether you could simply plug one of the differentials of the TX/RX of an RS422 to the Serial pins, or not.