Siemens SIMATIC S7-300 FM 350-1 Manual page 102

Operating Modes, parameters and commands
7.3 Count modes
Behavior at the Count Limits
If the counter
● has reached one of the count limits when counting without a main count direction,
● has reached the high count limit when counting with main count direction up, or
● has reached the low count limit when counting with main count direction down
and another pulse then comes, the counter is set to the load value, from which it resumes
counting. An appropriate status bit is set in the DB.
Table 7- 13
Count limit reached
High count limit
Low count limit
Terminating the Count with the Gate Stop Function
You can also terminate the count at any time with the gate stop function. Set the GATE_STP
input parameter of FC CNT_CTL1 for this.
102
Behavior at the Count Limits (Periodic Counting)
Status bit in DB
STS_OFLW is set
STS_UFLW is set
Manual, 05/2011, A5E03648639-01
FM 350-1 Counter module