Siemens simatic s7-400 FM 450-1 User Manual page 74

Modes, settings, parameters and commands
8.12 Initiating a process interrupt
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
Opening HW gate (level controlled)
Closing HW gate (level controlled)
Opening HW gate (edge controlled)
Closing HW gate (edge controlled)
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
Upper count limit
Lower count limit
Terminating counting process with the gate stop function
In addition you can terminate the counting process at any time using the gate stop function.
For this purpose you set the GATE_STP input parameter of the FC CNT_CTRL.
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Initiating event
Applying signal to input 1I0 (2I0)
Removing signal from input 1I0 (2I0)
Applying positive edge to input 1I0 (2I0)
Applying positive edge to input 1I1 (2I1)
Bit in the DB
STS_OFLW is set
STS_UFLW is set
Manual, 02/2014, A5E03648739-02
Counter module FM 450-1