Siemens simatic s7-400 FM 450-1, User Manual, Page: 82 / 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 the SW gate
The following figure shows the opening and closing of the SW gate of counter 1.
Figure 8-6 Opening and closing the SW gate
The SW gate is opened and closed by setting and resetting the input parameter SW_GATE
of the FC CNT_CTRL.
The closed gate can be reopened by setting the input parameter SW_GATE again.
Status of the SW gate
The status of the SW gate is signalized on the STS_SW_G bit of the DB of the
FC°CNT_CTRL.
Terminating the count with the gate stop function
In addition, you can terminate the counting process at any time using the gate stop function
of the relevant counter, irrespective of the signals applied or the status of the SW gate. For
this purpose you set the GATE_STP input parameter of the FC CNT_CTRL.
When you reset the GATE_STP parameter, you can only open the gate for the counter
concerned by means of a positive edge, either at input 1I0 or 2I0 (HW gate) or resetting the
SW_GATE input parameter (SW gate).
Hardware interrupt
Opening and closing of a HW or SW gate can be used to trigger a hardware interrupt (see
section "Initiating a process interrupt (Page 90)".)
Default setting
In the default setting all gates are open; the count pulses are counted.