Siemens SIMATIC ET 200AL, Системное руководство

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Counting
4.3 Examples of counting
Digital input/Digital output module DIQ 16x24VDC/0.5A 8xM12 (6ES7143-5AH00-0BA0)
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Equipment Manual, 08/2021, A5E38688112-AD
Behavior when a counting limit is exceeded - Continue counting (counting direction backward)
The following section describes the effects of the parameter "Behavior when a counting limit
is exceeded: Continue counting". To control the counter, the bits of the control byte of the
control interface are used, see the configuration method 2xCount, section Assignment of the
control interface (Page 43) and configuration method 4xCount, section Assignment of the
control interface (Page 62).
After the low counting limit is underpassed, the counted value jumps to the high counting
limit and counting is continued.
The bit STS_GATE is not reset when a count limit is exceeded.
The following figure shows an example of the principle of stopping counting when the low
count limit is exceeded, counting direction backward.
The behavior "Behavior DQ" is set to "Count value between a comparison value and the high
counting limit".
Figure 4-18 Principle: Continue counting (counting direction backward)
Reference
You will find general information on the counting function in the section Counting (Page 30).
Further information about the pin assignment, parameters, control and feedback interface,
etc. is available in the sections Configuration method 2xCount (Page 32) and Configuration
method 4xCount (Page 52).