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Rockwell Automation Publication 2080-UM002L-EN-E - November 2021
Chapter 8 Use the High-Speed Counter and Programmable Limit Switch
Programmable Limit Switch
(PLS) Function
The Programmable Limit Switch function allows you to configure the High-
Speed Counter to operate as a PLS (programmable limit switch) or rotary cam
switch.
When PLS operation is enabled (HSCAPP.PLSEnable = True), the HSC (High-
Speed Counter) uses PLS data for limit/cam positions. Each limit/cam position
has corresponding data parameters that are used to set or clear physical
outputs on the controller’s base unit. The PLS data block is illustrated in
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,
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.
LPReached
Input
BOOL
Low Preset reached.
This bit can be reset to FALSE when HSC is not counting.
OFOccurred
Input
BOOL
Overflow occurred.
This bit can be reset to FALSE when necessary.
UFOccurred
Input
BOOL
Underflow occurred.
This bit can be reset to FALSE when necessary.
Sts
Output
UINT
HSC function block execution status
Refer to HSC Function Block Status Codes on page 141 for
HSC status code description (except 0x02 and 0x04).
Table 37 - HSC Parameters (Continued)
Parameter
Parameter
Type
Data Type
Parameter Description
IMPORTANT
The PLS Function only operates in tandem with the HSC of a Micro830
controller. To use the PLS function, an HSC must first be configured.
Element Order
Data Type
Element Description
Word 0…1
DINT
High preset setting
Word 2…3
DINT
Low preset setting
Word 4…5
UDINT
High preset Output data
Word 6…7
UDINT
Low preset Output data
