Mitsubishi Q Series Programming Guide

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4 SFC PROGRAM CONFIGURATION
MELSEC-Q
4.7.1 SFC program start mode
The SFC program start mode setting determines whether an SFC program START (SM321 OFF
ON) is executed by an “Initial start,” or by a Resume start from the preceding execution status.
(1) Settings and corresponding operations
Set whether "initial start" or "resume start" will be selected for the SFC program.
(a) Initial start
The program is started after the active status at a previous stop is cleared.
The operation after a start is performed according to the setting of block 0 START condition.
(b) Resume start
The program is started with the active status at a previous stop (ON to OFF of SM321 or
RUN to STOP of CPU module) held.
The SFC program start mode changes depending on the combination of the setting of the
"SFC program start mode" in the PLC parameter dialog box and the ON/OFF status of the
"special relay for setting SFC program start status (SM322)" as indicated below.
Initial Start Resume Start SFC Program
Start Mode
Operation
SM322: OFF
(Initial status)
1
SM322: ON
(When changed by
user)
SM322: OFF
(Initial status)
1
SM322: ON
(When changed by
user)
SM321 is turned from OFF to ON Resume Initial
PLC power is switched OFF, then ON Resume/Initial 3 Initial
PLC power is switched OFF, then ON
after SM321 ON to OFF or RUN to STOP
Resume *2 Resume
2
Reset operation to RUN Initial Initial
Reset operation to RUN after SM321 ON
to OFF or RUN to STOP
Initial Initial
Resume
2 Resume 2
STOP to RUN Resume
STOP to program write to RUN Initial/Resume 5 Initial/Resume 4
Initial: Initial start, Resume: Resume start
1: SM322 is turned ON/OFF by the system according to the setting of the "SFC program start mode" in
the PLC parameter dialog box when the CPU module switches from STOP to RUN.
• At initial start setting: OFF
• At resume start setting: ON
2: Operation at resume start
At a resume start, the SFC program stop position is held but the status of each device used for the
operation output is not held.
Therefore, make latch setting for the devices whose statuses must be held in making a resume start.
• The held coil HOLD step SC becomes inactive, and is not kept held.
In the Basic model QCPU, the held coil HOLD step SC restarts in the held status. However, the
output is not held. To hold the output, make latch setting for the devices desired to be held.
3: Depending on the timing, a resume start is disabled and an initial start may be made. When it is
desired to make a resume start securely, turn SM321 from ON to OFF or switch the CPU module
form RUN to STOP, and then power the PLC OFF, then ON.
The Basic model QCPU always makes an initial start.

Mitsubishi Q Series Specifications

General

Brand	Mitsubishi
Model	Q Series
Category	Control Unit
Language	English