Kramer Electronics VS-4228 - Manual (Page 9)

6 VS-4228 - Overview
3.2 About RS-422
RS-422 control switchers differ substantially from video and audio switchers in
both design and in operation, as Sections 3.2.1 to 3.2.6 describe.
3.2.1 Signal Terminology
Connections are between master and slave or controller and controlled devices,
rather than the regular In and Out or source and destination devices. The
difference is not merely one of semantics but a vital distinction when trying to
understand the concept of RS-422 technology.
A regular In and Out switcher has separate input and output buttons on the front
panel and separate ports for input and output connectors on the rear panel.
A master and slave control switcher, has separate master and slave buttons on
the front panel but shared master/slave connectors on the rear panel.
3.2.2 Bi-directional Signals
By using a pair of conductors, each signal travels in both directions over a
balanced line between master/slave devices, as Figure 3 illustrates:
Figure 3: Bi-directional Signals I
When a master device changes position with a slave device, the pins automatically
change, as Section 3.2.4 describes and as Figure 4 illustrates:
Figure 4: Bi-directional Signals II