Mitsubishi MELSEC-A series, Programming Manual

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7. APPLICATION INSTRUCTIONS
7
−
126
MELSEC-A
2) The internal relay of which number (Y ) is same as the contact number
(X ) of forward stroke end sensors must be controlled as follows.
In forward run: Turn it ON.
In backward run: Turn it OFF.
(2) The CHK instruction executes processing equivalent to the circuit shown below
with one specified contact.
POINT
The CHK instruction performs error check following the circuit pattern
illustrated above. The circuit pattern cannot be changed.
M0
X Y
X X
CJ P0
CHK M0 D0
Max. 150 contact points
(Both of the forward stroke end and backward
stroke end sensors are actuated in forward run.)
Condition 1
Condition 2
Condition 3
Condition 4
Condition 5
Condition 6
X +1
SET M0
MOV D0
Error code 1
(Both of the forward stroke end and backward
stroke end sensors are actuated in forward run.)
X Y X +1
SET M0
MOV D0
Error code 2
(Backward run when the forward stroke end
sensor is actuated.)
X Y
SET M0
MOV D0
Error code 3
(Forward run when the backward stroke end
sensor is actuated.)
Y X +1
SET M0
MOV D0
Error code 4
(Forward run when the backward stroke end
sensor is not actuated.)
Y X +1
SET M0
MOV D0
Error code 5
(Backward run when the forward stroke end
sensor is not actuated.)
X Y
SET M0
MOV D0
Error code 6
Example Processing is performed as
X is X0, X +1 is X1 and Y is Y0.
P254