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APPENDIX
Telemetrics Serial Data Protocol
Telemetrics provides for serial control of many of our camera control products. This
summary briefly describes the protocol for serial control of these devices. In the
summary, the Telemetrics controlled device will be referred to as the “controller” and
the device commanding the controller will be referred to as the “host”.
Control is accomplished by sending commands consisting of ASCII characters
terminated by an ASCII carriage return (<CR>, hex 0D). In most cases, several
commands may be sent together on the same line before sending the <CR>. However,
in the case of the recall preset command, other commands may precede it but any
commands following it on the same line are ignored. A command line will not be
executed until the <CR> is received. ASCII backspace (<BS>, hex 08) can be used to
correct errors in the command line. After the command line has been executed, a
<CR> will be sent back to the host to acknowledge completion.
Communication rate is 9600 BAUD. Protocol is 8 data bits, one stop bit, and no parity.
Each command consists of either one or two letters, followed by any numerical
parameters needed for the command. (
Note
: The commands are CASE SENSITIVE.)
Numerical parameters are specified by the string of ASCII digits representing the
decimal value. For example, a value of 26 is sent as a ‘2’ followed by a ‘6’, (i.e., hex 32,
hex 36). Where a command has more than one parameter, the parameters should be
separated by a space. No other spaces are necessary, though they may be used if
desired.
Important Note
: In cases where the host does not monitor responding
carriage returns from the controller, the host will not know whether a command
line has been completed. The controller can receive new commands while it
is processing previous commands except when the controller is processing a
preset position recall. During a preset recall, all incoming characters are
ignored except for an ASCII cancel character (<CAN>, control-X, hex 18)
which tells the controller to abort the recall. Therefore, the host should send a
<CAN> preceding all command lines. This way, if a recall was in progress, it
will be aborted and the controller will accept the command. If no recall was in
progress, the <CAN> will be ignored.
The remainder of this summary describes the general methods for serial camera
control. Commands will be introduced as they are needed. Note that while examples
are shown enclosed in single quotes, only the characters within the quotes are to be
sent; the quotes are simply for clarity. In addition, the examples may use unnecessary
spaces for clarity, which need not be used for the actual application.
Manual Camera Motion
