Mitsubishi Electric MELSEC iQ-R Series Reference Manual page 30

■Program operation
When the inter-module synchronization cycle is coordinated with the fixed scan communication cycle for the multiple CPU
system function, the multiple CPU synchronous interrupt program (I45) and inter-module synchronous interrupt program (I44)
are executed between the inter-module synchronization cycles. The programs are executed in the order of multiple CPU
synchronous interrupt program (I45) and inter-module synchronous interrupt program (I44). It takes two inter-module
synchronization cycles for the host CPU module's retrieval data to reach another CPU module. To synchronize the output
between the CPU modules, the output timing from the host's control module must be delayed by two inter-module
synchronization cycles.
CPU No.1
Program execution
processing
Multiple CPU synchronous
interrupt program
Normal program
Operation processing
Input
Input data
module
1 Acquire an input value.
Fixed scan communication area
Fixed scan communication
Fixed scan communication area
Multiple CPU synchronous
interrupt program
Normal program
Operation processing
CPU No.2
Program execution
processing
(1) Write the input value into the CPU No.1's fixed scan communication area.
(2) Read the CPU No.1's fixed scan communication area, and set the output value.
An inter-module synchronization function FB is provided to absorb the two-cycle output difference. To delay
the output timing of the host's control module by two inter-module synchronization cycles, create a program
using the inter-module synchronization function's FB. (MELSEC iQ-R CPU Module Function Block
Reference)
5 FUNCTION
28
5.1 Fixed Cycle Synchronization Function
Fixed scan communication cycle
Inter-module synchronization cycle
Inter-module synchronous
interrupt program
Normal program
Input Output
Operation
refresh refresh
processing
Do not set data here even
though data can be output
at the next inter-module
synchronization cycle.
Fixed scan communication
Inter-module synchronous
interrupt program
Normal program
Input Output
Operation
refresh refresh
processing
Fixed scan communication cycle
Inter-module synchronization cycle
(1)
Fixed scan communication cycle
Inter-module synchronization cycle
Multiple CPU synchronous Inter-module synchronous
interrupt program interrupt program
Normal program
Input Output
Operation
Operation processing
refresh refresh
processing
2 Write data to the fixed
Do not set data here even
Output data
scan communication
though data can be output
area.
at the next inter-module
synchronization cycle.
Input data
Fixed scan communication
Input data
Multiple CPU synchronous Inter-module synchronous
interrupt program interrupt program
Normal program
Input Output
Operation
Operation processing
refresh refresh
processing
Fixed scan communication cycle
Inter-module synchronization cycle
Create the program where the two cycles of the output differences are offset.
Fixed scan communication cycle
Inter-module synchronization cycle
Multiple CPU synchronous Inter-module synchronous
interrupt program interrupt program
Input
Operation
Operation processing
refresh
processing
Output data
3 Fixed scan communication
4 Read data from the fixed scan communication area.
Multiple CPU synchronous Inter-module synchronous
interrupt program interrupt program
Input
Operation
Operation processing
refresh
processing
(2)
Fixed scan communication cycle
Inter-module synchronization cycle
Normal program
Output
refresh
Output data
5 Set an output value.
Fixed scan communication
Normal program
Output
refresh
Output data
5 Set an output value.
Output
module