Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 1436

Processing details
• This instruction activates the specified step in the specified block. The operation of the specified block will be as follows
depending on the status (active or inactive) of the specified block.
Status of the specified block
Inactive
Active
• If the instruction is executed to an active step, the instruction is ignored and processing will continue. Note that if the
specified step is holding the operating status, the hold status is reset. The step becomes a normal step, and executes the
action and transition.
• If the instruction is executed to an inactive block for which online change is being performed, the instruction is ignored and
processing will continue.
• When there are several initial steps, any of them can be selected and activated.
• If no block is specified, the following block is targeted depending on the execution program type.
• Sequence program: Block 0
• SFC program (within the action): Block where the instruction is executed (current block)
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
1434
13.1 SFC Control Instructions
Operation
The specified block is activated at execution of the instruction, and starts the processing from the specified step. If the
block start/end bit of the SFC information device is set, the corresponding bit device turns on.
The specified step is newly activated while the step which has already been active continues processing.