Lexmark 2380 - Forms Printer B/W Dot-matrix Service Manual page 24

Switch 11- Polarity For RS-422 Serial Interface (All Units):
NOR/REV reverses the polarity of the receive and transmit data line
for the RS-422 serial interface.
Switch 11
Off
On
Switch 12 - Serial Interface Mode Select: (All Units)
Switch 232/422 sets the serial interface in either
RS-232C or RS-422 mode.
Switch 12
Off
On
1-12
Mode
Normal
Reverse
Mode
RS-232C
RS-422