Delay transfer signal between 2 controller logix

Hello. I have main PLC L73 with redundancy module, and 4 others controller as L71, L72 (S/R A,B, CSU A/B). They connected through control net network as my attached document. I created message to read and write DINT, Real in main PLC L73 to others controller. I can read and write signal but sometime I have delay 20s to receive signal. Has anybody know my issue? How can I fix it? Thanks you

Hello:
You have fiber-optic media amongst other things. I always advise to check first things in the lower layers of the ISO/OSI model. I have not used ControlNet in many years. I would advice to check with the RSLogix the diagnostics of the ControlNet modules and see if it is reporting CRC errors or other errors (sorry, do not remember the details of the available counters). If you see errors increasing this is not good, obviously. Also, are these fiber optic couplers Rockwell devices? If these devices have a ControlNet address they should support diagnostics. If so, You should be able to access these diagnostic counters with RSNetworx and if there are problems in the fiber side this could provide useful hints. Maybe a little bit later other members of the forum may add more valuable hints. I hope this helps for now.

Thanks you for your reply. I really not experience with control net. It look like communication drop each 20-25s and reconnect.

Hello, as I said, some diagnostics information for the ControlNet brigdes, and if possible the ControlNet/Fiber optic couplers would be helpful.
Do you have access to a PC with RSLinx access to the Controlnet bridge? maybe from Ethernet/IP through logix bacplane to ControlNet bridge. I want to know if some unhealthy error counters are increasing in your system.