Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 1438

Precautions
• In a simultaneous sequence, specify and activate all the steps by using the SET instruction (Activating a step). If there is
any inactive step left, a convergence is not performed. Likewise, if the RST instruction (Deactivating a step) is executed to
a single step in a simultaneous sequence, a convergence condition is not satisfied.
• The current step No. cannot be specified within the action of the SFC program. If specified, an error occurs.
Operation error
Error code Description
(SD0)
31A1H The specified block does not exist. (SET/RST BL\S)
31A2H When a block No. is specified, the specified block No. is out of the range, 0 to 319.
31B1H The instruction is executed when no SFC program (scan execution type) exists or SM321 is off.
No specified step exists in the specified block. (SET/RST BL\S/S)
31B2H The specified step No. is out of the range, 0 to 511.
31B5H The current step is specified within the action.
13 SFC PROGRAM INSTRUCTIONS
1436
13.1 SFC Control Instructions