Siemens SIMATIC ET 200S Operating Instructions Manual page 138

1Count5V/500kHz
3.6 Count Modes
Direct loading of the counter does not cause the indicated stored count to be changed.
If you close the SW gate, counting is only interrupted; this means that when you open the
SW gate again, counting is continued. The DI digital input remains active even when the SW
gate is closed.
Counting is also latched and triggered in isochrone mode with each edge on the digital input.
The count that was valid at the time of the last edge before T
interface.
The Latch Function
In order to use this function, the Function DI parameter must be set to "Latch on Positive
Edge".
Figure 3-10
Count and latch value are preset with their RESET states (see RESET states table).
The counting function is started when the SW gate is opened. The 1Count5V/500kHz begins
at the load value.
The latch value is always the exact count at the time of the positive edge on the digital input
DI.
The stored count rather than the current count 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 count to be changed.
In isochrone mode, the count that was latched at the time of the last positive edge before T
is displayed in the feedback interface.
138
Latch with a Load Value of 0
is displayed in the feedback
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Technological Functions
Operating Instructions, 02/2007, A5E00124867-05
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