Omega OMP-MODL User Manual Download

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OMP-MODL

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HEORY OF

PERATION

A Program Net is a graphical representation of a sequence of commands. In the
process of transferring the Program Net to the OMP-MODL, the Program Net is
converted over to a sequence of commands. When Enabled, the OMP-MODL
microprocessor follows this sequence of commands to perform the desired functions.

During execution, the microprocessor steps through each of the commands,
completing the command if possible, then moving on to the next command. This
stepping through of commands can be visualized fairly accurately as propogating
through connections between icons in a Program Net.

In execution of a Program Net by the OMP-MODL microprocessor, an order of
operations is followed. The Program Net executes in approximately this order:

1. When a Sample Rate Clocks internal counter counts up to the

User specified sampling period (ie the Update pulse set within
the icon configuration dialog) the Sample Rate Clocks send out
their Update command to any connected icons.

2. Icons connected to the Sample Rate Clock(s) then update their

Outputs (eg taking a thermocouple temperature reading and
presenting the value on the Output)

3. Icons connected to these Outputs then receive the new signal

and process the signal and present it on their Ouput. This
processing then progresses through the remaining icons in the
Program Net from left to right.

4. When the processing has progressed completely through the

Program Net the OMP-MODL then waits (if any time remains),
waiting for the next Sample Rate Clock to generate an Update
command. If the Program Net specifies Seconds resolution
mode (Global Icon), the OMP-MODL goes into a low power
sleep mode to extend battery life.

5. When the Sample Rate Clock generates the Update command,

processing begins sequencing through the Program Net again.

During the execution of the Program Net, some parts of the Net may be skipped for
a number of reasons. Execution will then jump to the next part of the Net and
continue sequencing. Reasons that this might occur include:

♦

The sequence may run into an icon that is not Enabled.

♦

An icon may be encountered that has two inputs, where only one

input was recently processed, and the User has specified that
the Output is to be updated only upon Update of both inputs.

This explains why Program Nets will execute at different speeds if they contain
conditional statements. For example, a Program Net may be developed that
monitors a contact closure input (which can be done 100’s of times per second).
When the contact closes, 10 more channels may be enabled, storing data to
memory. The Program Net will slow accordingly. Also, different branches of a
Program Net may execute at different times if they are driven by Sample Rate
Clocks that have asynchronous (ie not synchronized) Update pulse rates specified by
the User.