Mitsubishi Electric MELSEC iQ-R Series Reference Manual page 28

• The inter-module synchronization timing is adjusted to the inter-module synchronization timing of the
master station by coordinating the inter-module synchronization function with the CC-Link IE Field Network
synchronous communication function. Therefore, the CC-Link IE Field Network synchronous
communication function must be set to use the inter-module synchronization function. ( Page 37
Settings in CC-Link IE Field Network)
• If the remote head module is disconnected, it cannot receive synchronous signals from the master station.
This state generates an error in the remote head module and stops the cyclic transmission, inter-module
synchronization, and CC-Link IE Field Network synchronous communication. After the remote head module
is returned, reset the module. ( Page 43 Program)
■Cyclic transmission in master station and remote head module
It takes two inter-module synchronization cycles for the remote head module's input/output refreshing state to be sent.
To synchronize the input/output refreshing between the master station and remote head module, the master station's input/
output refreshing must be delayed by two inter-module synchronization cycles.
An inter-module synchronization function FB is provided to absorb the two-cycle input/output difference. Use
the inter-module synchronization function FBs to create a program to delay the master station's input/output
refreshing by two inter-module synchronization cycles. (Page 40 Program,  MELSEC iQ-R CPU
Module Function Block Reference)
5 FUNCTION
26
5.1 Fixed Cycle Synchronization Function