In RTU Panel we are having several Analogue & Digital
Inputs /Outputs. We are recently facing some problems over
Analog inputs , which are not updating properly (But
Digital Input are updating normally) Can any one tell me
from where the problem is creating , we have checked PLC
CPU card, Analog Input card & we reconfigured ,But still
the issue is there.
Issue :
1. Sometimes Analog values are updating & sometimes not.
2. Analog values are not updating normally , showing some
wrong Values
3. Total dead (0 value)
Analog values are Level & flow measurement from the field
instruments.
(But in field the instruments are working normally &
Displaying the values normally in local display unit)
This problem we are facing in our Water Plant.
If any one experienced this same problem or having any
ideas related to our issue PLS send your valuable
Answers/Replies...

Answer Posted / dhaval jethva

Hi There........

As you have mention the problem,i can say that there is
definitely problem in two things (1) Scaling of that input
(2) Signal wire Coming from field instrument to your RTU
terminal.
If you dont find any problem above then do following Task
(3) if there is problem in only one channel of analog
terminal of RTU then By trial n error of by shuffling the
input you can verify where is the exact problem.

Please tel which i/p you are using Like is it 4 t0 20ma or
0 to 10 V from isolator of directly.

Regards
Dhaval Jethva

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