MVI46-GSC: Controlling Communications
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DCLittlejohn
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Friday 20 October 2006 4:17:52 am |
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MVI46-GSC: Controlling Communications
Aside from the sample ladder logic on the CD, is there any more examples of programming for the MVI46-GSC?
I have what I consider to be a simple task. My SLC program is supposed to ask 6 individually addressed pyrometers for the measured temperature. Each request (one address at a time) is supposed to be done individually, wait for a response (or timeout failure) and then move on to the next. Somewhere I am missing how to actually keep the GSC synchronized with my ladder, so I am copying responses into the wrong N registers in my ladder.
I would like to know just how to control the Tx and Rx buffers of the GSC without constantly accessing the M files (which slows the scan time down too much).
Anyone have some sample ladder they know works?
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jsanders
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Friday 20 October 2006 8:03:15 am |
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RE:MVI46-GSC: Controlling Communications
ProSoft's policy is to provide sample ladder logic for the MVIxx-GSC modules that shows how to properly move data into the Write Buffer and out of the Read Buffer with predictable and reliable result. It is not our policy to debug and troubleshoot application-specific logic created by end-users; although we will offer as much advise and support as we can on the best ways to use our products. We recommend you base any application on our sample and use the sample as is, without changes to the structure. This is because that, on this module, more than any other ProSoft module, the 'handshaking' or synchronization between the module's firmware and the ladder logic is critically dependent on the ladder's structure.
As a general recommendation, we advise using the exact structure of our sample ladder, as is, and inserting a JSR instruction between the Read and Write portions of our Process ladder. In your Subroutine(s), you would parse and process the input string and set up any out-going Write String. Any sequencing of out-going strings would also need to be handled in your Subroutine. That way, when your Subroutine ends and program execution falls back into our Process ladder, the outgoing string will be properly sequenced to the output buffer.
The details of why the structure is so critical are beyond the scope of this forum. If you wish additional details, please contact ProSoft Technical Support at (661) 716-5100 or e-mail your questions to: Support@psft.com.
Be advised that, while ProSoft encourages users to share ideas and programming techniques, we cannot be held liable for using programming examples from third-party sources.
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