Chapter 9
169
Logic programming – Function blocks
9.8.10 Switch synchronization
Function block diagram
General description
The Switch synchronization function block was designed to improve the integration of
SICK safety scanners (e.g. S3000). It monitors the input signals for changes. If a
change of any input signal has been detected, the function block “freezes” the values
of its outputs until the configurable Hold time for outputs has expired.
Parameters of the function block
Parameter Possible values
Cascade input With
Without
Antivalence check With
Without
If this function is active, the optional Antivalence error output can be
used.
Hold time for outputs
10 ms to 10 s in steps of 10 ms. The value has to be greater than
the logic execution time.
Invert input 1A …
Invert input 3B
Each input of this function block can be inverted (see Section 9.5.2).
Number of inputs or
Number of outputs
1 to 6
Use fault present With
Without
An inverted input will invert the corresponding output signal as well. E.g. if input 1A is
High, but configured as inverted, it will be evaluated as Low and output 1A will be set
to Low.
Hold time for outputs
The Hold time for outputs defines the time delay between the first change of any
input signal and the latching of the input signals, i.e. the reaction of the outputs. This
can be used to compensate delays e.g. between the different contacts of mechanical
switches.
Non cascading mode – without cascade input
If the Switch synchronization function block is configured without the Cascade input, it
supports the evaluation of up to three input pairs. A change of any input signal starts
the timer. The outputs 1A to 3B keep their values during the configured Hold time for
outputs. When the timer has elapsed, the values of the inputs 1A to 3B at this point of
time are applied to output 1A to 3B, irrespective of the result of the antivalence check.
The outputs keep these values until the next synchronization process occurs.
Figure 152:
Function block diagram for
the Switch synchronization
function block
Table 73:
Parameters of the Switch
synchronization function
block
Note
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