DH-485 comms issue node status dropping. HELP!!!!

I have a system consisting of a main plc (5/04) and 16 remote stations (5/03). The main plc has a 1761-Net-AIC which connects to the 16 remote stations through 1747-AIC link Couplers. All is well, and has been for years now, except Node #8 has intermittent communications drops lasting up to .6 of a second every few seconds or so. I found this through the S:67 data file in the main plc. The program monitors each node S:67/0-15 to look for communications between main plc and remote nodes and stop if an issue is found. I have changed out the 1747-AIC link coupler, cable and even the processor on node #8 thinking it might have a bad Ch0 comms port on it. None of these fixed the issue.

None of the other nodes have this problem and nobody can tell me exactly how long this has been happening.

Any help on this is appreciated. Thank You.

Taking back to the top.

Not much info to venture a guess.

Tell us more about the physical network, is node 8 in the middle of the daisy chain? Termination?

Is the main PLC using message instructions to communicate with the other PLC's?

If so is there something different about node 8's message instruction?

Is the main PLC giving enough time for each message instruction to complete?

16 nodes is pushing the limits for a DH485 network.

Ended up being caused by a 1747-AIC link adapter on one one of the nodes.