Siemens SIMATIC S7-300 FM 350-1 Manual page 95

Single Counting - Main Count Direction Down
In single counting mode with main count direction down, when the gate is opened, the
FM 350-1 counts up or down from the load value until the low count limit is exceeded.
If the low count limit is under-run, the following occurs:
● The gate is closed
● The STS_UFLW bit in the feedback interface is set
● The counter is loaded with the load value
The low count limit is 0. The load value has a starting count and can be changed.
You must open the gate again to restart the counting.
Figure 7-4 Single counting with main count direction down; canceling gate function
Selecting the Gate Function
You can select the gate control in this mode. The following options are available to you:
● SW gate
● Hardware gate, level-controlled or edge-controlled
FM 350-1 Counter module
Manual, 05/2011, A5E03648639-01
Figure 7-5 Single Counting with Load Value and gate control
Operating Modes, parameters and commands
7.3 Count modes
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