Chapter 9
167
Logic programming – Function blocks
9.8.9 User mode switch
Function block diagram
General description
The User mode switch function block selects an output depending on an input value.
Output x is High if Input x is High.
The function block supports 2 to 8 inputs and the corresponding outputs.
Only one input may be High at any time (1 out of n). If no input or more than one input
is High, the output that was High last is kept High for the configured discrepancy time.
After expiration of the discrepancy time, the Fault present output changes to High
and all outputs change to the value defined in the error output combination.
If in the first logic cycle after the transition from the Stop state to the Run state there is
no valid input combination, the configured error output combination is applied to the
outputs and the Fault present output changes to High immediately.
Parameters of the function block
Parameter Possible values
Discrepancy time 0 to 10 seconds in steps of 10 ms
Error output combination
Checked outputs will be High and not checked
outputs will be Low when Fault present is High.
Number of inputs or Number of outputs 2 to 8
Use fault present With
Without
Figure 150:
Function block diagram for
the User mode switch
function block
Table 71:
Parameters of the User
mode switch function block
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