Oki Microline Ml184T+ Handbook page 81

In addition to the cable, this serial interface has a piggyback circuit board
that must be installed in the printer. On the board are 16 function switches
(two sets of eight switches) that you may have to reset depending on the
model computer you connect to the printer.
Before installing the board, make sure the switches are set properly. The
function of each switch is as follows:
Switches 1, 2: Work together to regulate parity (odd, even, or no parity).
Factory set to no parity. You can reset the switches as shown
below.
Selection
Odd Parity
Even Parity
No Parity
Note: When the serial data 7 or 8-bits is set to 7, the parity must be set to either ODD or
EVEN. 7-bit serial data will not be printed correctly if the parity is set to None.
Switch 3: Factory set ON to select 8-bit data. Set this switch to OFF
if you have a 7-bit system.
Switch 4: Factory set ON for printer Ready/ Busy protocol. Set this
switch to OFF if your computer uses XON/XOFF protocol.
Switches 5, 6: Work together to enable you to run two serial cable tests:
one checks to ensure that you have the proper switch settings,
and the other checks the data cable to see if it is communicating
properly. The factory setting is the nontest mode, called
the print mode; page B-10 provides details about the circuit
and monitor tests.
Switch 1
ON
OFF
ON/OFF
Switch 2
OFF
ON
ON
Appendix B: Interface Cable B -- 7