Grass Valley Performer SD - Manual (Page 169)

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Serial Protocol Descriptions
Model 300 Compatible Protocol
Performer may be used as a Model 300 Production Switcher
peripheral. This protocol allows the Performer to reply to status
requests from the 300 and to execute video and audio selections
received from the (E-MEM) 300.
The Status Query command line is as follows:
Receive: 111XXX00 (XXX=Performer Poll Address, S2).
Send: 110XXX00 (XXX=Performer Poll Address).
0000VVVV (VVVV=video crosspoint 0-10, 0=no
source).
11112222 (1111=audio 1 crosspoint 0-10, 0=no
source).
11112222 (2222=audio 2 crosspoint 1-10, 0=no
source).
10100101 (Validity Code).
The Recall (Take) command line is as follows:
Receive: 110XXX00 (XXX=Performer Poll Address, S2).
0000VVVV (VVVV=video crosspoint).
11112222
(1111=audio 1 crosspoint).
11112222 (2222=audio 2 crosspoint).
10100101 (Validity Code).
Send: (nothing)
If the address, XXX, is different than the Performer address at
Switch S1, the command is ignored.
When a Status Query command is received, any crosspoint that
has a source of 0 is set to source 1 and audio crosspoint 2 is set to
be the same as audio crosspoint 1.
If a BREAK occurs, this purges any incomplete command and
begins a new command line. If any command is received in error
(wrong bit patterns), protocol error is called and the command is
ignored.
If a byte whose upper two bits are 11 is received when such a byte
is not expected, protocol error is called, any incomplete command
ignored, and the new byte honored as the beginning of a new
command.