Sfc Program Start Mode - Mitsubishi MELSEC-Q Series Programming Manual

4 SFC PROGRAM CONFIGURATION

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.
Operation
SM321: Turned ON
Programmable controller: Powered ON
Programmable controller: Powered OFF
and then ON after SM321 is switched
from ON to OFF or the CPU module is
switched from RUN to STOP
CPU module: Reset and RUN
CPU module: Reset and RUN after
SM321 is switched from ON to OFF or
the CPU module is switched from RUN to
STOP
CPU module: Switched from STOP to
RUN
CPU module: STOP, write a program,
and then RUN
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, Universal model QCPU, and LCPU, the held coil HOLD step SC
restarts in the held status under conditions other than those that turns OFF the coil HOLD step, such
as turning ON and OFF of SM321 or operating status change (RUN to STOP) of the CPU module.
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SFC Program
Start Mode
SM322: OFF
(Initial status)
Initial
Initial Start
SM322: ON
(When changed by
1
user)
Initial
Resume 7
Initial 4 5
Resume Start
SM322: OFF SM322: ON
(Initial status) 1 (When changed by
Resume
Resume/Initial 3
Resume 2
Resume/Initial 6
Resume 2
Initial: Initial start, Resume: Resume start
user)
Initial
Initial
Initial
Initial
Initial
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