Siemens SIMATIC ET 200S Operating Instructions Manual page 97

If you close the SW gate, it only interrupts counting; this means that when you open the SW
gate again, counting is continued. The digital input DI remains active even when the SW
gate is closed.
Counting is also latched and triggered in isochronous mode with each edge on the digital
input. The counter status that was valid at the time of the last edge before T
the feedback interface.
The Latch Function
In order to use this function, the Function DI parameter "Latch on Positive Edge" must be
selected for the digital input.
Figure 2-38
Counter status and latch value are preset with their RESET states (see corresponding table).
The counting function is started when the SW gate is opened. The 1Count24V begins at the
load value.
The latch value is always the exact counter status at the time of the positive edge on the
digital input DI.
The stored counter status rather than the current counter status is indicated in the feedback
interface. The STS_DI bit indicates the level of the latch signal.
Direct loading of the counter does not cause the indicated stored counter status to be
changed.
In isochronous mode, the counter status that was latched at the time of the last positive edge
before T
When you close the SW gate, the effect is either canceling or interrupting, depending on the
parameter assignment. The digital input DI remains active even when the SW gate is closed.
Further possible causes of parameter assignment errors with the latch function:
● Incorrect parameter assignment of the digital output function (Function DI)
Technological Functions
Operating Instructions, 06/2010, A5E00124867-07
Latch with a Load Value of 0
is displayed in the feedback interface.
i
1Count24V
2.9 Position feedback
is displayed in
i
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