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Configuration of synch

This section of the manual is not yet written. It will explain how to configure the synch. Some of these are settings in the [PLC] section, others are common to all modules, but they're all collected here because they logically belong together.

Introduction

There is no "global cycle" in MatPLC unless the user specifically configures one. By default, all modules run asynchronously, with semaphores making sure they don't step on each others' toes.

Explanation from a PLC background: the MatPLC reduces scan time at the expense of latency - at the top/bottom of the scan, it simply uses the latest available values rather than waiting for fresh ones. This is by default.

Using synch, the user can configure a global scan which interleaves scans of the ladder with refreshing the I/O, classical PLC style.

For modules like a modbus slave, one would normally leave it asynchronous, serving requests as they come in.

Similarly for any other modules that don't really belong in the global cycle. Perhaps they might even have a mini-global-cycle of their own - for instance, an I/O module and a corresponding DSP module might be synched together but not to anything else.

...

Not yet written - two methods, simple method, advanced method.

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$Date: 2003/09/05 11:36:00 $