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

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.
Settings and corresponding operations
Set whether "initial start" or "resume start" will be selected for the SFC program.
■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.
■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.
SFC Program Start Mode Operation
Start Mode
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: Switched from STOP to RUN
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: Reset and RUN
STOPRUN
CPU module: STOP, write a program, and then
RUN
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, 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.
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.
To perform a resume start, turn ON and then OFF SM321 or switch the CPU module from RUN to STOP, and power OFF and then ON
the programmable controller.
The Basic model QCPU and Universal model QCPU of which the first 5 digits of the serial number are "11042" always makes an initial
start.
*4 A resume start may be made depending on the SFC program change.
If a resume start is made as-is, a start is made from the old step number, leading to a malfunction of the mechanical system.
When any SFC program change (SFC diagram correction such as step addition and deletion) has been made, make an initial start once
and then return it to a resume start.
An initial start is always performed in the Basic model QCPU and the Universal model QCPU with serial number (first five digits) "11042"
or earlier.
*5 In the Universal model QCPU and LCPU, a resume start is performed if data other than SFC programs are changed.
4 SFC PROGRAM CONFIGURATION
120
4.7 SFC Operation Mode Setting
Initial Start
SM322: OFF SM322: ON
*1
(Initial status) (When changed by
user)
Initial Initial
*7
Resume
*4*5
Initial
Resume Start
SM322: ON SM322: OFF
*1
(Initial status) (When changed by
user)
Resume Initial
*3
Resume/Initial Initial
*2
Resume Initial
*6
Resume/Initial Initial
*2
Resume Initial