Tektronix Phaser 840, Service Manual

Page: 22 / 207

Service Guide 11
An internal data bus, called the I
2
C bus, connects all I/O boards to the main
board. Through this single bus, the main board can “poll” the I/O boards for the
state of the printer’s sensors as well as actuate the printer’s solenoids. This data
bus greatly simplifies the wiring that would otherwise be required for monitoring
numerous sensors and solenoids. The I
2
C bus also extends down to the High-
capacity Paper Trays.
The printer’s I
2
C bus
0388-05
I
2
C bus
High-capacity
Paper Tray
connection