Ricoh A193 Service Manual page 419

Main
Frame
All components (motors, sensors, solenoid and switches) are controlled by
the finisher drive board and the communication between the main frame and
finisher uses a serial signal.
When the finisher is connected, the finisher connection signal (finisher set) to
the main frame is grounded. Then, the main frame will detect that the finisher
is connected.
(A666)
Finisher Drive Board
Finisher Drive Baord
/TXD
/ R S D
Finisher
Connection
12-17
DETAILED DESCRIPTIONS
Motors
Solenoid
Sensors
Switches
SM