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

00.000000

99.12399.123000

7ML19985AB01

OCM III

107

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Image 106
Siemens instruction manual Typical OCM-3, Display value, 00.000000 99.12399.123000 7ML19985AB01, 107