En And Eno - Mitsubishi Electric MELSEC Q Series Programming Manual

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.
EN
TRUE (Operation execution)
FALSE (Operation stop)
• A setting of an output label to an ENO is not essential.
• As for application functions, functions with an EN are shown as "Function name_E".
Ex.
Usage example of EN and ENO
(1)
No. Control description
(1) When the EN input is directly connected from the left power rail, the EN input is always TRUE and the instruction is always executed. If the
ADD_E instruction is used in this manner, the operation result is the same as the ADD instruction without the EN input.
(2) When Variable_1 is connected to the EN input, the instruction is executed when Variable_1 is TRUE.
(3) When the result of Boolean operation is connected to the EN input, the instruction is executed when the result of Boolean operation is TRUE.
(4) When the ENO outputs are connected to the EN inputs, three instructions are executed when Variable_1 is TRUE.
(5) When the ENO outputs are not connected, the execution result of the instruction is not output.
ENO
TRUE (No operation error)
FALSE (Operation error)
FALSE
(2)
(3)
Operation result
Operation output value
Undefined value
Undefined value
(5)
(5)
(5)
(4) (4)
4 PROGRAM CONFIGURATION
4
(5)
27
4.2 POUs