Sfc Program Resumptive Start Procedure - Mitsubishi Electric MELSEC-Q Series Programming Manual

SFC program resumptive START procedure

The SFC program START format can be designated as "initial START" or "resumptive START". The "resumptive START"
setting procedure as well as some precautions regarding the "resumptive START" format are described below.
Resumptive START setting procedure
Make the resume START setting of the SFC program in the "SFC Program Start Mode" of the SFC setting in the PLC
parameter dialog box.
Block operation status resulting from "SFC Program Start Mode" setting
At an SFC program start, whether an initial start or resume start will be made is determined by 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)".
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  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. 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. Note that the Basic
model QCPU and the Universal model QCPU with serial number "11042" (first five digits) or earlier always perform 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. Note that the Basic model QCPU
and the Universal model QCPU with serial number "11042" (first five digits) or earlier always perform an initial start.
*5 In the Universal model QCPU and LCPU, a resume start is performed if data other than SFC programs are changed.
*6 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.
• When the programmable controller is powered OFF or the CPU module is reset, the intelligent function
modules and special function modules are initialized. When making a resume start, create an initial program
for the intelligent function module/special function module in the block that is always active or in the
sequence program.
• When the programmable controller is powered OFF or the CPU module is reset, values in the devices
without a latch setting are cleared. To hold the values in the SFC information devices, set a latch range.
SFC Program Start Mode
Initial Start
SM322: OFF SM322: ON
*1
(Initial status) (When changed by
user)
Initial Initial
Resume
*4*5
Initial
Resume Start
SM322: ON SM322: OFF
*1
(Initial status) (When changed by
user)
Resume Initial
*3
Resume/Initial
*2
Resume
*6
Resume/Initial
*2
Resume
6 SFC PROGRAM EXECUTION
6.1 SFC Program START and STOP
6
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