Grass Valley Switcher Products - Manual (Page 93)

Switcher Products — Protocols Manual 93
Section
3
Peripheral Bus II Protocol
Introduction
This section describes the Peripheral Bus II (PBus II) serial protocol and
related commands, which can be used to allow a master (controlling)
device to control external (controlled) devices that support the protocol.
Controlling devices able to use the Peripheral Bus II protocol include the
Kalypso Video Production Center and the Zodiak Digital Production
Switcher. In this section these devices are referred to by the generic term
“switcher”. Earlier Grass Valley Group switchers (Model 200, 250, 3000,
4000, and 2200) also use the Peripheral Bus II protocol, acting as controlling
devices. However, some very early Grass Valley Group switchers (Model
300, 1600/1680) use a different protocol (called the Peripheral protocol),
which is incompatible with the Peripheral Bus II protocol described here.
Programming a controlled device to communicate properly with the
switcher requires a thorough understanding of the protocol and the avail-
able commands. Controlled devices may be programmed to support dif-
ferent sets of the available PBus II commands.
Overview
System Description
The Peripheral Bus II system consists of a single controlling device (the
switcher) and up to 24 peripheral controlled devices connected to a serial
bus (
Figure 7 ). The controlling device communicates with controlled
devices via a serial connection. All devices on the bus must operate at the
same baud rate, parity, and communication standard (RS-485).