We have 4 ammonia storage tanks in our plants commissioned after one another. All of them are having Honeywell Enraf 854 ATG series installed on them. All of them are having the same issue that randomly Enraf data from the LT disappears. It happens once in 6 to 8 months but it happens. What could be the root cause behind it?

 

Sometimes this phenomenon can be caused by timing on the fieldbus, e.g. when many simultaneous diagnostic messages occur, or simply by old field wiring.