Mitsubishi Q Series Programming Guide

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6 SFC PROGRAM EXECUTION
MELSEC-Q
6.2 Block START and END
6.2.1 Block START methods
The block START methods during SFC program execution are described below.
As shown below, there are several block START methods. Choose the method which is most
suitable for the purpose at hand.
START Method Operation Description Remarks Block 0
Other than
Block 0
Auto START using PLC
parameter
•
By setting the "start condition" to "block
0 Auto START" in the SFC setting of the
PLC parameter dialog box, block 0 is
automatically started at an SFC program
start, and processing is executed from
the initial step.
•
Convenient when block 0 is
used as a control block, a
preprocessing block, or a
constant monitoring block, for
example.
Block START by SFC
diagram symbol
•
Another block is started by the block
START steps (Bm
, Bm ) at each of
the SFC program blocks.
m
Transition condition
satisfied
n
Bm
Block No. to be started
Block m is started.
•
Convenient when the
sequence control is clear as
in automatic operation.
•
There are 2 types of block
START:
The START source step
remains active until the
START destination block is
ended.
The START source transition
occurs without waiting for the
START destination block to
be ended (SFC diagram
symbol: Bm
).
Block START by SFC
control instruction
•
Using an SFC control instruction, a
specified block is forcibly started from an
SFC program step (operation output), or
from another sequence program.
(1) When specified block is executed
from its initial step:
Condition
sBLm
m is the block No.
(2) When specified block is executed
from specified step:
Condition
sBLm\Sn
m is the block No., n is the step No.
• Convenient when starting an
error reset processing block
at error detection, etc., and
for executing interrupt
processing, for example.
Block START by SFC
information device
•
The corresponding block is activated by
forcibly turning ON the "block
START/END bit", which was set to each
block as the SFC information device, in
the program or peripheral
device.information register.
•
Convenient for debugging
and test operations in 1-block
units because the block can
be started from a peripheral
device without requiring a
program.
: Usable, : Unusable

Mitsubishi Q Series Specifications

General

Brand	Mitsubishi
Model	Q Series
Category	Control Unit
Language	English