JVC
Command Format
The
Section | Size | Comments |
Header | 1 byte | Can be one of four possible values – see below |
Unit ID | 2 bytes | Fixed – always 89 01 |
Command | 2 bytes | See below |
Data | Variable | Length varies depending on command – see below |
End | 1 byte. | Fixed – always 0A |
Taking each of these sections in turn:
Header
The header can be one of 4 possible values. These are:
21 – Operating Command (from PC/controller to projector)
3F – Acknowledgement Response return Code Request (from PC/controller to projector)
06 – Acknowledgement Response Return Code – Basic (from projector to PC/controller)
40 – Acknowledgement Response Return Code – Detailed (from projector to PC/controller)
Unit ID
This is fixed at 89 01 for all models.
Command
This is the command sent to/from the projector and varies depending on the command. As an example, the Power Command is 50 57. The other commands can be worked out from the tables on pages
Data
This is the value to apply to the command. Using the Power example above, the data value for Off is 30 and the data value for On is 31.
End
This signifies the end of the command and is fixed at 0A for all models.
Putting all this together, a typical command (Power On) to the projector would therefore be:
Header | Unit ID |
|
| Command | Data | End | ||
21 | 89 |
| 01 | 50 |
| 57 | 31 | 0A |
Error Handling
The projector will ignore any commands that it cannot recognise, e.g. Unit ID does not match, parity error, invalid command, etc. It will also ignore any inappropriate commands, e.g. Power On when in cooling mode.
The projector will discard any commands received if there is a break of 50ms or longer in the incoming data.
If consecutive commands are used, it is assumed that any external controller will not transmit a command until it has received an appropriate Acknowledgement Response Return Code to confirm that the projector is ready to accept the next command (see page 11 for details).
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