Pls Data Structure; Pls Operation - Allen-Bradley Micro830 Manual

Chapter 8 Use the High-Speed Counter and Programmable Limit Switch
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The PLS Function only operates in tandem with the HSC of a Micro830
IMPORTANT
controller. To use the PLS function, an HSC must first be configured.

PLS Data structure

The Programmable Limit Switch function is an additional set of operating modes
for the High Speed Counter. When operating in these modes, the preset and
output data values are updated using user supplied data each time one of the
presets is reached. These modes are programmed by providing a PLS data block
that contains the data sets to be used.
PLS data structure is a flexible array, with each element defined as follows,
Element Order Data Type
Word 0...1 DINT
Word 2...3 DINT
Word 4...5 UDINT
Word 6...7 UDINT
The total number of elements for one PLS data cannot be larger than 255.
When PLS is not enabled, PLS data are still required to be defined, but can be
not initialized.

PLS Operation

When the PLS function is enabled, and the controller is in the run mode, the
HSC counts incoming pulses. When the count reaches the first preset (HSCHP
or HSCLP) defined in the PLS data, the output source data (HSCHPOutput or
HSCLPOutput) is written through the HSC mask (HSCAPP.OutputMask).
Element Description
High preset setting
Low preset setting
High preset Output data
Low preset Output data
Rockwell Automation Publication 2080-UM002K-EN-E - March 2019