Lexmark 4039-1XX - Manual (Page 64)

50 Service Manual
4039-1XX
Switch 11 – Polarity for RS-422 Serial Interface: Switch 11 is
used to reverse the polarity of the receive and transmit data line for
the RS-422 serial interface.
Switch 12 – Interface: Switch 12 sets the serial interface in either
RS-232C or RS-422 mode.
11 Mode
Off Normal
On Reverse
12 Mode
Off RS-232C
On RS-422