Block Start/End Bit - Mitsubishi Q series Programming Manual

4 SFC PROGRAM CONFIGURATION

4.5.1 Block START/END bit

The block START/END bit is used to confirm the active status of the specified block by a
sequence program or the test operation of the peripheral device.
It can also be used as a device to forcibly start or forcibly end the specified block.
(1) Operation of block START/END bit
(a) The block START/END bit turns ON when the corresponding block starts.
The block START/END bit remains ON while the corresponding block is active.
(b) The block START/END bit turns OFF when the corresponding block becomes inactive.
The block START/END bit remains OFF while the corresponding block is inactive.
Block 0
S0
t0
S1
t1
S2
B1
t2
(2) When the corresponding block is inactive, it can be started independently by forcibly turning
ON the block START/END bit.
While the corresponding block is active, the processing of the corresponding block can be
forcibly ended by forcibly turning OFF the block START/END bit.
The block START/END bit can also be turned ON/OFF in the test mode of the peripheral
device.
(3) When a forced OFF is executed by the block START/END bit, and the block in question
becomes inactive, processing will occur as follows:
(a) Execution of the block in question will stop together with all outputs from the step which
was being executed. (Devices switched ON by the SET instruction will not switch OFF.)
(b) If another block is being started by the block START step in the corresponding block, the
corresponding block stops.
However, the start destination block remains active and continues processing.
To also end the start destination block simultaneously, the block START/END bit of the
start destination must also be turned OFF.
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Block 1
S0
t0
1)
S1
t1
S2
t2
2)
"Block START/END bit" of block 1: M0
1)
M0
ON
OFF
MELSEC-Q
2)
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