Please follow following procedure to test your on board RS-422/485 port. For example, if we want to test ECM-3412’s RS-422/485 :
1. The Avalue board which support RS-422/485, it contains one serial port could be selected as RS-232, RS-422, or RS-485 by setting jumper, Please change related jumpers to RS-422 or RS-485 jumper setting.