Siemens simatic s7-400 FM 450-1, User Manual, Page: 74 / 130

Modes, settings, parameters and commands
8.12 Initiating a process interrupt
Counter module FM 450-1
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Manual, 02/2014, A5E03648739-02
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
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.