Fixed Scan Function Information - Mitsubishi Electric MELSEC iQ-R Series User Manual

Fixed scan function information

The following is the list of special relay areas relating to the fixed scan function information.
No. Name
SM480 Cycle error flag for inter-
module synchronous
interrupt program (I44)
SM481 Cycle error flag for multiple
CPU synchronization
interrupt program (I45)
SM484 Execution section excess
error flag for multiple CPU
synchronization interrupt
program
SM488 Inter-module synchronization
error (out of synchronization
was detected on the CPU
module)
APPX
654
Appendix 4 List of Special Relay Areas
Data stored
Off: No error for the inter-
module synchronization
program (Normal)
On: Error state for the inter-
module synchronization
program
Off: No error for the multiple
CPU synchronization
program (Normal)
On: Error state for the
multiple CPU
synchronization program
Off: No execution section
excess error for the
multiple CPU
synchronization interrupt
program (Normal)
On: Execution section
excess error state for the
multiple CPU
synchronization interrupt
program
Off: No error (Normal)
On: Error
Details
• This relay switches to on when the inter-module
synchronous interrupt program (I44) has not been
completed within the specified inter-module
synchronization cycle or the program cannot be
executed due to various reasons, such as execution of a
higher-priority interrupt program and interrupt disabling
by the instruction execution.
• The ON state is maintained even after the program is
later completed within the specified inter-module
synchronization cycle (Clear by turning power off and on
or resetting).
• This relay switches to on when the multiple CPU
synchronization program (I45) has not been completed
within the specified fixed scan communication cycle or
the program cannot be executed due to various reasons,
such as execution of a higher-priority interrupt program
and interrupt disabling by the instruction execution.
• The ON state is maintained even after the program is
later completed within the specified fixed scan
communication cycle (Clear by turning power off and on
or resetting).
• This relay switches to on when the program is executed
exceeding the program execution section within the
specified multiple CPU synchronization cycle.
• The ON state is maintained even after the program is
later completed within the multiple CPU synchronous
interrupt program execution section (cleared by turning
power off and on or resetting).
• This relay switches to on when the inter-module
synchronization signal cannot be identified within the
inter-module synchronization cycle specified in the
parameter or more than one signal has been identified
within the same inter-module synchronization cycle.
• The ON state is maintained even after the inter-module
synchronization signal can be later identified within the
specified inter-module synchronization cycle (cleared by
turning power off and on or resetting).
Set by (setting
timing)
S (Status change)
S (Status change)
S (Status change)
S (Status change)