JVC RS-232C - Manual (Page 20)

JVC D-ILA Projector Remote Control Guide
Page 20 of 25
Command Format
The RS-232C commands are bidirectional and consist of a variable number of hexadecimal
numbers. All of the commands sent to the projector shown in this guide are either 7 bytes or
10 bytes long. The Acknowledgement Response Return Codes returned from the projector
can be between 6 and 14 bytes long. The basic format of the commands is as follows:
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 3-13.
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 of 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 detected, 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 15 for details).