Chapter 9
194
Logic programming – Function blocks
9.9.6 Light curtain monitoring
Function block diagram
General description
The Light curtain monitoring function block allows the implementation of a
semiconductor protective device functionality with ESPE.
The internal logic of the Light curtain monitoring function block corresponds to the
functionality of the Emergency stop function block, however with a limited parameter
selection. The single-channel input type cannot be selected in the Light curtain
monitoring function block. When the evaluation of the complementary inputs is High,
the Enable output is High (see Section 9.9.2).
If a corresponding dual-channel input element is configured in the hardware
configuration of the Setting and Monitoring Tool, this function block is no longer
required in the logic since the pre-evaluation is then carried out directly on the safety
I/O module (e.g. WS0-XTDI or WS0-XTIO module). But if the Fault present output is
required for further processing, the function block can be used to this purpose. To this
purpose the two input signals have to be configured as single-channel signals and
applied to the inputs of the function block.
Parameters of the function block
Parameter Possible values
Inputs Dual-channel equivalent
Discrepancy time 0 = disabled, 10 to 500 ms in 10 ms steps. If enabled, the value has
to be greater than the logic execution time.
Number of outputs 1 (Enable output)
2 (Enable output and Discrepancy error output)
Use fault present With
Without
Figure 181:
Function block diagram for
the Light curtain monitoring
function block
Note
Table 85:
Parameters of the Light
curtain monitoring function
block
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