PID with digital output

[nvhung.mctt]

Hi,

I have the application.

I do not clear about PID function but, I would like to ask you about my application.

I have a sensor water level and a few motors to control gates

I measure water level and control motor via digital output(using the fieldpoint system)

I would like to hold water level at level, so I use PV indicator  and SV control. when I change SV then will  control Motor (RW or FW motor).
 
Can we use how technology to hold water level PV=SV  ?.

Please let me know your comments.

Thanks

Nguyen Van Hung

[Trey_C]

Hi Nguyen,

There are several examples in CVI under Help » Find Examples that may be able to help speed up the development of your PID program (assuming you have purchased the CVI PID Toolkit).  These examples can be found by going to Toolkits and Modules » PID and Fuzzy Logic Control » PID.  Depending on how familiar you are with PID algorithms, I might suggest that you look at the GeneralPid example first.  Additionally, the PID Control Toolkit User Manual t is also a great place to look at the algorithms and the library functions.  Finally, in case you aren't aware, you can double click on any function that you find in the Libraries folder located in the bottom left of CVI to open a functions panel which will show all inputs and outputs of a given function.  Then, you can right click on any parameter to view details about that or on the function panel (outside an input box) for more information about the function in general.

I hope these resources help you design an algorithm that works well for your situation!

Regards,

Trey C.

Applications Engineer

National Instruments

[nvhung.mctt]

Hi Trey C.

Thanks for your information that you have provided.

I have seen a few exmaples for PID, but I only see with analog output. However, I still will continue reseach it, but I have not much time, so I would like to get information to solve my application in the short time.

Best Regards,

Nguyen Van Hung

[Trey_C]

Nguyen,

Examples with an analog output are definitely much more common as this is the most prevalent use case; however, I hope that the information I provided can give you a general understanding of how to use the PID Toolkit in CVI.  

There is one forum post that I've looked through before where someone is using digital outputs with his PID and, while this is mainly discussing the application in LabVIEW, I believe it would still be helpful to give you ideas.  The first part of the thread is general troubleshooting but I believe that, starting on page 3, you should find some information more specific to what you are trying to do.

Good luck with your project!

Regards,

Trey C.

Applications Engineer

National Instruments