hwRsPortMode 1.3.6.1.4.1.2011.5.25.157.1.23.3.1.2

This object indicates the type of a serial interface. The value can be rs-232,rs-485,rs-422,,v.24,x.21 or v.35. For AND1MPAA PICs: Ports 0 and 2 work in rs-232 mode. The working mode cannot be configured. Ports 1 and 3 can work either in rs-485 or rs-422 mode. The default mode is rs-422. For AND1SA8 PICs, all ports can work in v-35, x-21, or v-24 mode. The default mode is v-24.