1 MULTIPLE CPU SYSTEM
1.3 Data Communication Between CPU Modules in the Multiple CPU System
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Data communication by refreshing at Motion CPUs
This section describes data communication by refreshing at Motion CPUs.
Refresh timing
The refresh timing at Motion CPUs differs from that for PLC CPUs. The refresh types and refresh timing are as follows.
*1 This is an interchangeable setting equivalent to the MELSEC Q series "High-speed refresh" setting.
*2 The order of processing inside the Motion CPU is as follows.
"Motion SFC event task Receipt refresh Motion operation Transmission refresh"
*3 The order of processing inside the Motion CPU is as follows.
"Receipt refresh Motion SFC event task Motion operation Transmission refresh".
Furthermore, if the operation cycle is shorter than the fixed scan communication cycle, receipt refresh and transmission refresh are
performed only at the operation cycle immediately after the fixed scan communication cycle.
If using refresh (fixed scan communication), it is recommended that fixed scan communication cycles and
Motion operation cycles be aligned.
Refresh type Memory used Refresh timing
PLC CPU side Motion CPU side
MELSEC iQ-R series Refresh (END) CPU buffer memory At END processing Main cycle
Refresh (Q compatibility
high-speed refresh)
*1
Operation cycle and main cycle
*2
Refresh (I45 executing) Fixed scan
communication area
When executing Multiple CPU
synchronous interrupt program (I45)
The longer of the operation cycle or
fixed scan communication cycle
*3
MELSEC Q series
(iQ Platform compatible)
Automatic refresh At END processing Main cycle
High-speed refresh The longer of the operation cycle or
0.888ms and main cycle
*2
Motion CPU
fixed-cycle
processing
Motion operation cycle
Fixed scan communication cycle
Receipt refresh
Fixed scan communication
data transmission section
Transmission refresh
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