Behavior At The Counting Limits - Siemens SIMATIC ST-1500 Function Manual

2.2 Basics of counting, measuring and position input (TM Count, TM PosInput, Compact CPU)
2.2.4

Behavior at the counting limits

Violation of a counting limit
The high counting limit is violated when the current counter value is equal to the high
counting limit and another upward count pulse is received. The counter low limit is violated
when the current counter value is equal to the counter low limit and another downward count
pulse is received.
The appropriate status bit is set in the feedback interface in the event of limit violation:
Counting limit violated
High counting limit
Low counting limit
You can reset the status bits with RES_EVENT .
You can configure whether or not and from which counter value counting is to continue
following counting limit violation.
Note
The high counting limit and the start value define the value range of the counter:
Value range of the counter = (high limit – start value) + 1
Examples
The figure below shows an example for terminating the counting process (automatic gate
stop) after an overflow and setting the counter to the start value:
Counting, measurement and position detection
Function Manual, 12/2017, A5E32009889-AG
The basics of counting, measurement and position detection
Status bit
EVENT_OFLW is set
EVENT_UFLW is set
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