Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 99

Coil HOLD step [SC]
Coil HOLD step [SC] is a step that holds the outputs of a coil that has been turned on by the action even after the active state
transitions.
(2)
Y10 (1) that has been turned on by using the OUT instruction remains on (3) even when the transition (2) becomes TRUE.
No operation in the action is performed after a transition becomes TRUE and the next step is activated. Therefore, the coil
output status will remain unchanged even if the input condition in the action is changed.
■ Timing of when coil output turns off
The coil output holding ON state is turned off in the coil HOLD step [SC] after transition when:
• The end step of a block is executed (other than the case where SM327 is on).
• A block is forcibly terminated by using the RST instruction (Ending a block).
• A step is reset by using the RST instruction (Deactivating a step).
• The device specified as the block START/END bit of the SFC information devices is reset.
• A reset step [R] for resetting the coil HOLD step [SC] becomes active.
• SM321 (SFC program start/stop) is turned off.
• The coil is reset by the program.
• The stop instruction is executed with theoutput mode at block stop set off.
• S999 is specified at a reset step [R] within a block.
■ Operation when the block is paused or restarted
Operation when the block is paused or restart depends on the combination of the SM325 (Output mode at block stop) status,
block stop mode bit setting of the SFC information device, and step hold status. ( Page 133 Operation when the block is
paused or restarted)
Operation HOLD step (without transition check) [SE]
Operation HOLD step (without transition check) [SE] is a step which continues the operation of the action even after the active
state transitions.
This step continues the operation in the action even after a transition becomes TRUE and the next step is activated.
Therefore, when the input condition changes, the coil status also changes.
After the transition becomes TRUE and the next step is activated, the transition is not checked and the transition to the next
step does not occur.
(1) (3)
(2)
■ Deactivation timing
An operation HOLD step (without transition check) [SE] becomes inactive when:
• The end step of a block is executed.
• A block is forcibly terminated by using the RST instruction (Ending a block).
• A step is reset by using the RST instruction (Deactivating a step).
• The device specified as the block START/END bit of the SFC information devices is reset.
• A reset step [R] for resetting the operation HOLD step (without transition check) [SE] becomes active.
• SM321 (SFC program start/stop) is turned off.
• S999 is specified at a reset step [R] within a block.
Y10
ON ON
(1)
Y10
ON
(3)
Y10
X0
When step (2) is activated, step (1) holds the operation.
While holding the operation, the transition is not checked but the action (3)
is kept executed.
In this case, Y10 turns on or off accordingly as X0 turns on or off.
8 SFC PROGRAM
97
8.2 Structure
8