Mitsubishi Electric MELSEC-Q Series Programming Manual page 18

A given function can be controlled in a variety of ways according to the application
Block functions such as START, END, temporary stop, restart, and forced activation and ending of specified steps can be
controlled by SFC diagram symbols, SFC control instructions, or by SFC information registers.
Control method
Control by SFC diagram symbols
Control by SFC instructions
Control by SFC information devices
Functions which can be controlled by multiple methods are shown below.
Function
Block START (with END wait)
Block START (without END wait)
Block END
Block STOP
Restart stopped block
Forced step activation
Forced step END
In cases where the same function can be executed by a number of methods, the first control method which has been
designated by the request output to the block or step in question will be the effective control method. Functions controlled by
a given control method can be canceled by another control method.
Ex.
For block START, the active block started by the SFC diagram can be forcibly ended by executing the SFC control instruction
before the END step or by turning OFF the block START/END bit of the SFC information devices.
Automatic scrolling function enables quick identification of machine system troubles
The execution of an active (execution) block, an active (execution) step, an operation output/transition condition can be
monitored (with the automatic scrolling function) from peripheral devices. Moreover, the transition watchdog function enables
the detection of the step where transition does not occur after the designated time elapses. These monitoring functions allow
you to track down the spot where a problem occurs without a broad knowledge about sequence programs.
1 GENERAL DESCRIPTION
16
1.2 SFC (MELSAP-L) Features
Description
Convenient for control of automatic operations with easy sequential control.
Enables requests from program files other than the SFC, and is convenient for error processing, for example after
emergency stops, and interrupt control.
Enables control of SFC peripheral devices, and is convenient for partial operations such as debugging or trial runs.
Control Method
SFC Diagram
Bm
Bm



Sn
SFC Control Instructions

sBLm
rBLm
PAUSE BLm
RSTART BLm
• sSn
• sBLm\Sn
• rSn
• rBLm\Sn
SFC Information Registers

Block START/END bit ON
Block START/END bit OFF
Block PAUSE/RESTART bit ON
Block PAUSE/RESTART bit OFF

