Grass Valley Switcher Products - Manual (Page 103)

Switcher Products — Protocols Manual 103
Commands
Read Command
The controlling device sends a Read command to a selected controlled
device to request the contents of the controlled device’s register. The con-
trolled device responds with a Write response (see
page 104 ). If there is no
reply from the controlled device within four (4) television fields, the con-
trolling device assumes that the device is not capable of executing the com-
mand.
The format of the Read command is:
Rddrrr
• The first byte is the ASCII keyword for Read, R (52H).
• Next a two-byte field of ASCII characters (dd) representing a hex
number is sent that corresponds to the controlled device number (00H-
17H).
• Next three ASCII characters (rrr) are transmitted, representing the hex
number of the register which the controlling device wants to read
(000H-FFFH)
• A carriage return ends the message.