MVP 2021 Flex727 Posted May 27, 2011 MVP 2021 Report Share Posted May 27, 2011 I have limited experience with the Unitronics PID function and desperately need some help. I am using a V570 with an IO-AI4-AO2 I/O Expansion and VisiLogic 8.6.3. I am connecting a pressure sensor (4-20ma) to AI0 and controlling a pump on AO0, also with 4-20ma. I have set up a PID control loop using the example file in VisiLogic, but some of the configuration MIs are a bit confusing. Can someone provide a common sense explanation for some of the less obvious ones? For example, the PV high and low limit - what are these values doing? I understand the limits on CV, but not PV. Also, I am unable to get the Autotune PID Server to work properly. I was able to get it online with the PLC with all the MIs set, but when I run the Server, nothing happens - there is no data exchange with the I/O module. Any helpful hints? Lastly, this is an extremely simple control loop and could probably work well with proportional control only. Can I & D be turned off? Either way, what are some basic starting values I should input into the configuration MIs to at least get me down the road to tuning the control loop? Quote Link to comment Share on other sites More sharing options...
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