Siemens SIMATIC ET 200SP Manual page 16

Product overview
2.2 Functions
Capture (Latch)
You can configure an external reference signal edge that triggers the saving of the current
counter value as Capture value. The following external signals can trigger the Capture
function:
● Rising or falling edge of a digital input
● Both edges of a digital input
● Rising edge of the N signal at the encoder input
When using a digital input, you can specify whether counting is to continue from the current
counter value or from the start value after the Capture function. When using the rising edge
of the N signal at the encoder input, counting is to continue from the current counter value
after the Capture function.
Synchronization
You can configure the edge of an external reference signal to load the counter with the
specified start value. The following external signals can trigger a synchronization:
● Rising or falling edge of a digital input
● Rising edge of the N signal at the encoder input
● Rising edge of the N signal at the encoder input depending on the level of the assigned
digital input
Hysteresis
You can specify hysteresis for the comparison values, within which a digital output will be
prevented from switching again. An encoder can come to a standstill at a specific position,
and slight movements may make the counter value fluctuate around this position. If a
comparison value or a counting limit lies within this fluctuation range, the corresponding
digital output will be switched on and off with corresponding frequency if hysteresis is not
used. The hysteresis prevents these unwanted switching operations.
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Technology module TM PosInput 1 (6ES7138-6BA00-0BA0)
Manual, 04/2016, A5E33015755-AC