Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 152

■ Operation when a target block is activated during the online change (inactive SFC block)
A target block is not activated when the target block is attempted to be activated while the online change (inactive SFC block)
is executed. The following table describes operations depending on block start methods.
Start method (activation method)
Auto-start by the CPU parameter setting
Block start step (without END check)
Block start step (with END check)
SFC control instructions (SET BL, SET S, SET BL\S
instructions)
SFC information device (start by the block start/end bit)
Start by the engineering tool
*1 A target block is not activated by the auto-start set in the CPU parameter while the online change (inactive SFC block) is being executed.
*2 This indicates the following activation methods: Changing values of BL and BL\S on the watch window or the device/buffer
memory batch monitoring window and selecting an item in Control SFC steps under Debug.
In the STOP or PAUSE status, an active step holds its active state. Therefore, the online change (inactive
SFC block) to a block holing the active state cannot be executed.
■ Precautions
• Do not power off or reset the CPU module while the online change (inactive SFC block) (including transfer of data to the
program memory) is being executed. If doing so, write the data to the programmable controller again.
• The online change (inactive SFC block) and the following operations from the engineering tool cannot be executed
simultaneously.
• Online change (ladder block), write to the programmable controller, or online change (inactive SFC block)
• Write to the programmable controller (excluding device, local device, global label, or local label data)
• Memory initialization
• When deleting the OUT instruction (coil) which is not necessary for control, be sure to check that the OUT instruction is off
before deleting it. If the OUT instruction is deleted without turning it off in advance, the output will be retained.
• If a subroutine-type FB is called within the changed ladder block, information of the last execution, such as instructions
executed at the rising edge or falling edge within the FB definition of the called subroutine-type FB, is not initialized.
• When the online change (inactive SFC block) is executed, the start-up of an interrupt program may be delayed. Therefore,
when the execution time is monitored (Error Detections Setting of the CPU parameter) for the interrupt program that uses
the inter-module synchronous interrupt (I44) and multiple CPU synchronous interrupt (I45), an error may be detected in the
CPU module. ( MELSEC iQ-R CPU Module User's Manual (Application))
• Some sections are not targeted for the scan monitoring while the online change (inactive SFC block) is executed, and
therefore a WDT error may not be detected even though the scan time set in the scan time monitoring time (WDT) setting is
exceeded.
• When an instruction is executed during the online change (inactive SFC block) and an error is detected, a step number
stored as the error location information is the one in a program being written. The step number after the completion of
writing is not stored.
• The online change (inactive SFC block) cannot be executed in the following cases.
• A target program file is not registered in the corresponding parameter.
• The number of SFC steps exceeds the number of step relay points set in the device setting of the CPU parameter.
• Operating status of the CPU module is switched to STOP and data are written to a specified program or a parameter in the programmable controller.
(The function cannot be executed until the operating status of the CPU module is back to RUN.)
• Program execution error (error code: 3204H) has been detected.
8 SFC PROGRAM
150
8.7 SFC Program Execution
*2
Operation at block start
*1

• A target block is not activated until the online change (inactive SFC block) is completed.
Even when a transition following a step is TRUE, the next step does not become active.
• A target block is activated after the online change (inactive SFC block) is completed.
When a transition is TRUE, the next step becomes active.
• A target block is not activated until the online change (inactive SFC block) is completed.
• A target block is activated after the online change (inactive SFC block) is completed.
When the block ends and a transition following a step is TRUE, the next step becomes
active.
A target block is not activated. If an instruction contact remains on, the target block is
activated after the online change (inactive SFC block) is completed.
A target block is not activated even when the block start/end bit turns on. When the block
start/end bit is on, the target block is activated after the online change (inactive SFC
block) is completed. (The system does not activate the target block until the function is
completed.)
A target block is not activated. A request is ignored. (The system does not activate the
target block until the online change (inactive SFC block) is completed.)