Siemens SIMATIC S7-300 FM 350-1 Manual page 94

Operating Modes, parameters and commands
7.3 Count modes
Single Counting - Main Count Direction Up
In single counting mode with main count direction up, when the gate is opened, the
FM 350-1 counts up or down from the load value until the high count limit is exceeded.
If the high count limit is exceeded, the following occurs:
● The gate is closed
● The STS_OFLW bit in the feedback interface is set
● The counter is loaded with the load value
The high count limit can be set. The load value has a starting count and can be changed.
You must open the gate again to restart the counting.
Figure 7-3 Single counting without main count direction; canceling gate function
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FM 350-1 Counter module
Manual, 05/2011, A5E03648639-01