Mitsubishi Electric MELSEC iQ-F FX5 Programming Manual page 739

■Operation of program
The step ladder program operates as follows.
SM402
SET S31
STL S31
*1
SM400
Y30
*1
SM400
SET Y31
X1
SET S32
STL S32
*1
SM400
*5 Y30
Y32
X2
S33
*1 It is always necessary to program to drive an output.
*2 Output coils can be used again in different state relays.
*3 Each OUT and SET instruction for step relays automatically resets the transfer source, and has the self-holding function.
*4 One step relay number can only be used once.
*5 It is not possible to place a pointer immediately after the STL instruction. If a pointer is placed, a program error (33E2H) occurs.
When the step relay is latched, the ON/OFF status is backed up by nonvolatile memory against power failure.
Use this type of state relay if the operation should be restarted from the last point before power failure. These
relays hold the operation status also at the time of RUN to STOP. If it RUN(s) again, the operation will be
resumed from the State before STOP.
■Related devices
Device Name
SM8040 STL transfer disable
SM8046 STL state ON
SM8047 Enable STL monitoring
SD8040 to SD8047 ON step relay numbers
Precautions
When the step relay is not latched, step relay clears at power supply ONOFF or RUNSTOP. If the State is valid and power
supply ONOFF or PLC RUNSTOP, operation can not be restarted from the last point before power-supply ONOFF or
RUNSTOP.
Operation error
There is no operation error.
*2
Process of S31
When X1 turns ON, S32
turns ON and S31 is
*3 automatically reset.
*4
*2
Process of S32
*3
Remarks
When SM8040 is set to ON, transfer of the ON status is disabled among all state relays.
When the step relay turns on, SM8046 turns on automatically.
When SM8047 is turned on, it stores in SD8040 to SD8047 sequentially from the young number of
the step relay which operates in the step relay.
The turned-on step relay number is stored in SD8040 to SD8047 (Max. 8 points) sequentially from
the smaller number.
SM402
SET S31
STL S31
SM400
Y30
SM400
SET Y31
Y31 programmed in the
SET instruction remains
X1
ON even if S31 is reset.
SET S32
STL S32
SM400
Y30
Y32
X2
S33
9 STEP LADDER INSTRUCTIONS
Activated
9.1 Starts/Ends Step Ladder
9
737