Mitsubishi Electric MELSEC iQ-R Series User Manual page 122

Even if a CPU which does not use the fixed scan communication function exists, it will not cause an error by
setting the send area of the fixed scan communication area for the CPU with the fixed scan communication
function set to "Not Use" (that is, unset) in the host CPU parameter setting. This is because the unset CPU is
regarded as a reserved CPU for future setting.
(Example) When the host CPU is set as CPU No.1 and "Fixed Scan Communication Function" is set to "Not
Use" for CPU No.4 in a system configured with four CPUs
Perform fixed scan
communication.
communication area
(Receive area of CPU No.1)
(Receive area of CPU No.1)
(Receive area of CPU No.1)
12 BUS ACCESS FUNCTION
120
12.2 Data Communication Between CPU Modules
Perform fixed scan
communication.
Fixed scan
communication area
CPU No.1
(Host CPU)
Send area of
CPU No.1
Send area of
CPU No.2
Send area of
CPU No.3
Send area of
CPU No.4
Perform fixed scan
communication.
Fixed scan Fixed scan
communication area
CPU No.2 CPU No.3
(Other CPU) (Other CPU)
Send area of Send area of
CPU No.1 CPU No.1
Send area of Send area of
CPU No.2 CPU No.2
Send area of Send area of
CPU No.3 CPU No.3
Send area of Send area of
CPU No.4 CPU No.4
Do not perform fixed
scan communication.
Fixed scan
communication area
CPU No.4
(Other CPU)
Since the fixed scan
communication setting is
disabled, data is not sent to
other CPUs although the area
is reserved. Data from other
CPUs is not received.