Lexmark T522 Service Manual - Page 158

4520-xxx Autoconnect System, Paper Tray Options, Envelope Feeder Electrical Autoconnect Cabling and Connectors The printer options make electrical connection automatically, requiring no external cables when the option is mechanically installed under the printer. Communication between the option and the base printer stops when you remove an option. The printer no longer recognizes the option and deletes associated messages. Each installed option below the base printer provides an electrical autoconnect to the option attached below it. We do not recommend to attach or "Hot Plug" any options with the base printer power turned on. Duplex Unit The duplex unit interface is a six pin autoconnector that provides a +24 V dc, +24 V dc return, serial interface transmit signal, serial interface receive signal and two ground pins. The duplex unit receives the +24 V dc from the base printer for the duplex motors and also converts the voltage to +5 V dc for duplex electronics. Duplex chassis grounding is provided from the printer to the duplex unit through a ground spring attached to the frame and base of the printer. The ground connection is automatically made when the option is installed below the printer. The paper input sensor is located in the rear of the duplex unit under the input paper guide. The paper exit sensor is located on the left frame assembly. Option Microcode The options are "Smart Options" or options that have a system board. The option system board has a microprocessor that controls the option mechanism. A software architecture is provided that controls the option and communicates information such as paper path status, sensor status, motor status and so on to the base printer. 3-26 Service Manual