Serial Data Communication

The printer communicates with and controls the Paper Feeder, the Lower Cassette Assembly, and the Envelope Feeder through serial data lines SLI and SLO. In addition, the DC Controller uses information encoded on SLI from the High Voltage Transformer to monitor the toner level.

Communicating with the various subassemblies of the printer through serial data lines allows many of the functions of the processor on the DC Controller to be off-loaded to local State Machines on the subassemblies. The DC Controller uses data line SLI to receive status information (such as Ready, or Paper Out) from the subassemblies. Data line SLO is used to issue commands or to request status.

The State Machines on the subassemblies operate on a clock synchronous to the DC Controller processor. The printer serial data lines use serially encoded data protocol to receive and send information.

Figure 5-2 Serial Data Flow

5-4 Functional Overview