We have a Honeywell TPS system installed at our site. I keep getting a suspect alarm on only LCN cable B. I have local Honeywell service engineer check all LCN cable segments and MAUs. The problem goes for some time and then comes back again. When I look at the generated error from LCN diagarm menu, it keeps jumping between different nodes. My problem is that the alarm comes at times, clears itself or after we reset all timers and bounce back again after few days.

Appreciate any suggestions.

Thanks,

Fayez
alanziff @ yahoo. com

 

A thumb rule to be followed in "ill equipped" areas like Process Plant:

Check which node is registering highest number of noise counts.
Attend that node throughly... Remove cable, push it in again and turn it clockwise till you get a "click" feel of the BNC...
If you can change MAU, better....
If you can change cable, better....

A better idea about the faulty node can also be had from the Node specific view menu (LCN Diagnostics ---> Cable B Rates). Select each node and see which one gives the max number of noise counts.

Resetting the counts will not help. Even if the counts are present, the Cable B suspect message can be cleared. What matters is that the counts shouldnt increase... They must remain wherever they are.

We face a similar problem with 02 node... and it's identified with the BNC connection with the MAU. The cables are in stress and it leads to the BNC connector to "loosen" a bit after some time... Usually while tightening the connector a "click" feel ensures it's properly connected. We "missed" that feel and found that the BNC would not settle in the locking groove. So eventually owing to the cable twists and strains, it would loosen and cause the Noise on the Cable.

au revoir
Rahul

 

Hi Fayez,

I think it's better you check all LCN cables too. You can ask your local Honeywell Engineer to verify your LCN cables status. He should have the tool (TDR).

To make sure everything is fine, you can also ask him to perform system performance baseline (SPB).