Actuator feedback is connected to a MNL controller and displays a negative '%open position.

Issue

A customer installed a critical valve with an actuator containing a potentiometer for a positional feedback connection.
The potentiometer was wired into a MNL controller's input.
After some calibrating, the potentiometer drives past the "0 %open" position which displays as a negative value in the AI point.

Is there a way to compensate in software for this negative reading?

Product Line

TAC I/A Series

Environment

WorkPlace Tech

MNL and MNB controllers

Cause

It can be difficult to calibrate the feedback potentiometer accurately.

Resolution

Add a high selector block to the output of the AI block.  Connect the AI block's output and a constant set to a value of zero.

Anytime the AI block's output drops below zero, the output of the high selector will display zero.  This can then be used for other logic or for graphical display.