4.3. Changing Monitor Pins
The four internal jumpers located on the CAS-41A circuit board can be used to switch the
CAS-41A to monitor pin 4 (Request to Send) instead of pin 20 (factory setting). To switch
monitor pins, proceed as follows:
CAUTION: Make certain to power off the CAS-41A and disconnect the power
cable before attempting to remove the instrument cover.
1. Switch off power to the CAS-41A and disconnect the AC power cable from the power
2. Remove the four screws that secure the CAS-41A's plastic cover to the chassis. Remove
the cover from the chassis.
3. Locate the jumpers on the CAS-41A circuit board. As you face the instrument back
panel, the jumpers are located in the lower left hand corner of the circuit board.
Figure 4.1 describes the jumper settings for selecting Pin 4 or Pin 20.
4. Replace the plastic cover on the CAS-41A chassis. Reinstall the four screws that secure
the cover to the chassis. Reconnect the power cable and switch the
Figure 4.1: Jumper Positions for Pin Selection