Siemens OCM III, Instruction Manual, Page: 106 / 112

Custom Programming and Third Party Communication Program
Users who wish to write their own software to communicate with the OCM-3 are urged
to implement a fully buffered (interrupt driven) serial link incorporating XON/XOFF.
Some users however, will not have the capacity for such an undertaking. Those users
may still communicate with the OCM-3 using the less sophisticated communication
capabilities provided by such high level languages as Basic, Pascal or C. The only
restriction imposed by using a system that does not use XON/XOFF, is that the user
must insure that he does not send long streams of commands to the OCM-3 without
pausing periodically to allow the OCM-3 time to process them.
Most users who wish to write their own software to communicate with the OCM-3 will
do so for a specific purpose. An example would be to create a customized data log.
For this, the user will want that only the numeric values be returned, and none of the
descriptive information.
To achieve this, the OCM-3 provides a secondary command parser which is accessed
when the OCM-3 receives a command enclosed by ‘/’. When the leading ‘/’ is detected
by the primary parser, the OCM-3 diverts the message to the secondary parser. The
secondary parser remains in control until it receives the trailing ‘/’.
If the trailing ‘/’ is not received within a few seconds, the secondary parser is aborted
and control is reverted to the primary parser automatically.
The OCM-3 response message to a command to the secondary parser is a sequence
of ASCII characters terminated by an ASCII carriage return (hex 0D) and an ASCII
line feed (hex 0A). All system parameters and most other responses are floating point
numbers with a maximum of 6 decimal places.
e.g. typical OCM-3 response
display value message
0 0.000000
99.123 99.123000
7ML19985AB01 OCM III 107