Mitsubishi MELSEC-F FX-TRN-BEG-E, User Manual

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FX-TRN-BEG-E B: Let’s Study the Basics 2
B-21
2.3.3 Points of training and control specifications
1) Interlock program (in which precedence is given to the first input)
The interlock program is used to give precedence to an input operated first to avoid any
unwanted interruption by another operation.
The principle is often used to control the forward/reverse rotation command of motors or the
ON/OFF status of a solenoid valve with possible safety hazards.
Example
• Enter Y001 as the NC contact for OUT
instruction Y000.
Enter Y000 as the NC contact for OUT
instruction Y001.
• The example demonstrates an interlock
operation whereby Y0 and Y1 can never
be set ON simultaneously.
*A: As Y000 is set ON by X024, Y001 does not turn ON even if X025 turns ON.
*B: When X024 turns OFF, Y000 is turned OFF. Subsequently, Y001 turns ON.
*C: As Y001 is set ON by X025, Y000 is not turned ON even if X024 turns ON.
2) Interlock program (in which precedence is given to the last input)
In the interlock program in example 1) outlines a precedence to the first input. However, the
precedence can similarly be given to the input condition that has most recently come true.
Example
• The precedence is given to either X020 or
X021 which is input last, and the Y000 or
the Y001 turns ON accordingly.
X024
Y000
X025
Y001
Y000
Y001
Interlock program
X024
Y000
X025
Y001 *A
*B
*C
X020
Y000
Y000
X021
X021
Y001
Y001
X020
Interlock program
Please note that if either
input X20 or X21 is to be
kept ON, precedence is
given to the first input.
If you want to give the last
input precedence in this
case, use the rising/falling
edge detection instruction
explained in the next
exercise.