Siemens Metro 21 M216KA, Руководство оператора

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13-8
ET 200L, ET 200L-SC and ET 200L-SC IM-SC Distributed I/O Device
EWA 4NEB 780 6009-02c
13.3.2 Gate Functions
Many applications require counting to start or stop as of a defined time, de-
pendent on other events. In the case of the counter module, this starting and
stopping of counting is effected by means of a gate function. If the gate is
opened, count pulses can get through to the counter. If the gate is closed,
count pulses can no longer get through to the counter and counting stops.
The counter module has a gate function. This is controlled by the user pro-
gram in the CPU. The transmission times must be taken into account here.
When the gate signal is set, the gate is opened and the count pulses are
counted. When the gate signal is taken away, the gate is closed and the count
pulses are no longer registered by the counter. The count remains constant.
Figure 13-11 shows the opening and closing of a gate and the counting of the
pulses.
Count
Count pulses
Gate signal
Opening
of the gate Closing of
the gate
4
1 2 3 4
Figure 13-11 Opening and Closing of a Gate
You can terminate counting by setting the ”gate” bit to ”0”.
Counting with
Gate Functions
Gate Function
Example
Terminating
Counting with the
Gate Stop
Function
The 1COUNT40kHz Counter Module