In 800xA system where i can check the Overflow and Underflow range parameter and also how to change the parameters.
Thanks in advance
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Typically these are defined as per the type of AI/AO modules and the type of signal range, configured per channel (4-20mA, 0-20mA...), and can't be changed by the user.
Look in the help of Control Builder for the type of module, and you will see the standard values for underflow and overflow for different modules and signal ranges.
For some of them there are different fixed selectable values for underflow - from the help file:
4-20 mA gives an underflow at < 2mA.
4-20 mA < 3.65, gives an undeflow at <3.65.
4-20 mA < 3.8, gives an underflow at <3.8
You also have a possibility to go outside that limits by setting of the parameter "Clamp Analog in values" to False - for Controller HW object. But see the remark from help about that:
"For most of the analog input units the output signals are not allowed to go outside the scaling range of 0-100%, no matter whether this parameter is set to true or not"
Source: Control Builder Help
In AC800M you can check Overflow and underflow values in settings.(attached picture)
But (In AC800m)you can not change underflow and overflow range other than system defined limits.
In AC460(MOD) you can change underflow and ovreflow ranges by modifing counts in FCM template.
Following thread of mine.(for your reference)