The NARS2 adaptor is used to connect the SATELLINE 3AS radio modem to a balanced (or differential) RS422 or RS485 transmission line.
Balanced Transmission uses two lines on each signal and are more immune to induced noise than conventional RS232 so that longer cables can be used. However it must be noted that with longer cables differential transmission lines should be terminated to prevent reflections
RS422 interface used two signal pairs, one pair in TX and the other in RX
RS485 uses only one single pair and multiple devices can be connected to the same lines, in this case termination is necessary only at the first and last device
The NARS2 adaptor contains terminating resistors which can be set to on or off by the user