Grass Valley Switcher Products - Manual (Page 45)

Switcher Products — Protocols Manual45
Kalypso/Zodiak Editor Protocol
break/address sequence. Responses (handshakes or read data) are
returned in the same order as the command/message blocks are received.
Byte Count
The command/message block can range in size from two to 256 bytes. The
first byte of the block contains the byte count. A byte count consists of the
total number of subsequent bytes in the block; valid byte count values
range from 01H to FFH (1 to 255). After receiving a valid byte count (01H
to FFH) and the proper number of data bytes (1 to 255), the switcher exe-
cutes the command.
Effects Address Byte
The second byte of the command/message block is the effects address byte,
typically referred to as EX. This byte identifies the desired “effect bank”
within the switcher where the associated command will go. Valid Effects
Addresses for each command are specified later in this manual.
Command Code Byte
The command code is the third byte of the command/message block.
Command codes fall into two broad categories: requests and commands.
Only one command is allowed in any command/message block. Likewise,
only one response is embedded in any command/message block.
Requests
Requests interrogate the status of the specified operational parameter of
the switcher. When the editor issues a read command/message block, the
switcher responds by sending the current status of the requested opera-
tional parameter(s) back to the editor. This status information is returned in
the format of the write command/message block. By echoing the write
format, the editor can later send responses to a request to the switcher and
cause execution of that function.
Commands
Commands are used by the editor to change operational parameter(s) or
initiate a function within the switcher.