Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 122

■ Precautions
• Do not use the SFC control instructions in interrupt programs.
• Execute the SFC control instruction only when SM321 (SFC program start/stop) is on.
Index modification
The step relays and SFC block devices specified by SFC control instructions can be index-modified.
Device
SZ
BL\SZ
BLZ\S
BLZ\SZ
BLZ
The step relays and SFC block devices can be specified within the following range, including the case of index modification.
Device
S
BL\S BL
S
BL
For details on index modification, refer to the following.
 MELSEC iQ-R CPU Module User's Manual (Application)
8 SFC PROGRAM
120
8.3 SFC Control Instructions
Index modification target part
Step relay
Step of step relay with block specification
Block of step relay with block specification
Block and step of step relay with block specification
SFC block device
Range
0 to 16383 (the maximum value is set by a CPU parameter)
0 to 319
0 to 511
0 to 319