Siemens FM 450-1 - Page 63

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8SSHUFRXQWOLPLW
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Figure 8-3 Periodic counting with load value and gate function
Open and close SW gate
You open and close the SW gate and set the counter to the load value by setting or resetting the
relevant bit in the DB of the FC°CNT_CTRL in the user program (see chapter "Assignment of the
DB (Page 87)"). When you open the SW gate, the FM 450-1 starts counting from the load
value.
Action Initiating event
Open SW gate Set SW_GATE
Close SW gate Reset SW_GATE
If you want to restart the counter, you must reset the bit. The counter then starts counting from
the load value.
Opening and closing HW gate
You open and close the HW gate and set the counter to the load value by applying or removing
the relevant signals at the inputs 1I0 and 1I1 (counter 1) and/or 2I0 and 2I1 (counter°2).
Action Initiating event
Opening HW gate (level controlled) Applying signal to input 1I0 (2I0)
Closing HW gate (level controlled) Removing signal from input 1I0 (2I0)
Opening HW gate (edge controlled) Applying positive edge to input 1I0 (2I0)
Closing HW gate (edge controlled) Applying positive edge to input 1I1 (2I1)
If in the case of an edge controlled HW gate a positive edge is again applied to input 1I0 (2I0),
the relevant counter again starts counting from the load value irrespective of whether the gate
is closed or still open (retriggering) provided input 1I1 (2I1) is not set.
Behavior at the Count Limits
If a counter reaches the upper or lower count limit and a further count pulse comes, it begins
counting from the load value again. The count process is thereby continued without pulse loss.
A corresponding status bit is set in the DB:
Count limit reached Bit in the DB
Upper count limit STS_OFLW is set
Lower count limit STS_UFLW is set
Modes, settings, parameters and commands
8.6 Periodic counting
Counter module FM 450-1
Equipment Manual, 03/2022, A5E03648739-AC 63