What are the best practices for overflow / underflow

We are actually working on DCS migration from 800xA / DCI to 800xA / AC800M.

The actual 800xA version is 5.0 SP2 Rev.C. It will be upgraded at the end of migration.

For some type of measures (especially pH), the plant told us it's normal for them to get overflow / underflow. When it happens they want the PidCC to keep working as usual to let pid go to 0% or 100%. For those loops, we set the error handling to through on the SignalOutRealM. By doing this, the process control works with overflow/underflow, but it will also work with a channel error.

I also noticed the clamp analog value settings. I'm wondering if it could be a good option in this case. They have AI815.

How would you deal with overflow and underflow in this case?



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asked 4 months ago



For Underflow/Overflow, Check channel settings.

Eg: Measure mA for that channel at 0 and 100 %, it should match 4 and 20 mA. If value measured is lower than 4mA then it shows underflow. For this We need to change the settings of channel from 4-20mA to some nearer value from drop down which matches with measured value.


answered 4 months ago


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