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FX
/FX
/FX
Series Programmable Controllers
3G
3U
3UC
Programming Manual - Basic & Applied Instruction Edition
35.1.5 Latched (battery backed) type state relays
In the latched (battery backed) type state relays, the ON/OFF status is backed up by the battery or EEPROM
memory against power failure.
Use this type of state relays if the operation should be restarted from the last point at power recovery after
power failure occurred in the middle of machine operations.
35.1.6 Role of RET instruction
• Use RET instruction at the end of an SFC program.
When inputting an SFC program using GX Developer, however, it is not necessary to input RET instruction
(because RET instruction is automatically written).
• In a PLC, two or more SFC blocks can be put between step 0 and the END instruction.
When there are ladder blocks and SFC blocks, put RET instruction at the end of each SFC program.
35.1.7 Preliminary knowledge for creating SFC program
List of sequence instructions available in states
Initial/general state relay
Branch/
recombination
relay
• STL instruction cannot be used in interrupt programs and subroutine programs.
• When using SFC programs (STL instruction), do not drive state relays S using SET or OUT instructions in
an interrupt program.
• It is not prohibited to use jump instructions in state relays. However, it is not recommended to use jump
instructions because complicated movements will result.
*1.
The MPS instruction cannot be used immediately after a state relay (STL instruction), even in a drive
processing circuit.
808
State relay
Drive processing
state
Transfer processing
LD/LDI/LDP/LDF,
AND/ANI/ANDP/ANDF,
OR/ORI/ORP/ORF,
ANB/ORB/MPS/MRD/
INV,MEP/MEF,
OUT,SET/RST,
PLS/PLF
Available
Available
Available
35 SFC Program and Step Ladder
35.1 SFC Program
Instruction
MC/MCR
MPP
*1
Not available
Available
*1
Not available
Available
Not available
Not available
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