Specifications

4.2 POUs
4.2.9 EN and ENO
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4
PROGRAM CONFIGURATION
4.2.9 EN and ENO
An EN (enable input) and ENO (enable output) can be appended to a function and function block
to control their execution.
A Boolean variable used as an executing condition of a function is set to an EN.
A function with an EN is executed only when the executing condition of the EN is TRUE.
A Boolean variable used as an output of function execution result is set to an ENO.
The following table shows the status of ENO and the operation result according to the status of
EN.
Table 4.2.9-1 Status of ENO and the operation result according to the status of EN
1. A setting of an output label to an ENO is not essential.
2. As for application functions, functions with an EN are shown as ‘Function
name_E’.
EN ENO Operation result
TRUE (Operation execution)
TRUE (No operation error) Operation output value
FALSE (Operation error) Undefined value
FALSE (Operation stop) FALSE Undefined value