Micrologix 1500 analog

[Programmer4]

I just recently finished a project using analog inputs and outputs with the micrologix 1500 and it was not so easy. It is actually a little difficult understanding the the scaling and pid functions.

 

[bernie_carlton]

Is it the scaling and PID functions as they are implemented in the Micrologix 1500 in particular or do you have a problem with understanding scaling and PID functions in general?

 

[Ron Beaufort]

I just recently finished a project

does it work? ... if you just need a "check up" then ZIP your .RSS file and post it ... we'll be glad to take a look at it for you ... maybe we can make the next time easier ...

and by the way, if it DOES work, congratulations!

 

[Programmer4]

Its just understanding the pid and scaling in general, and if you have any great rules that I could go by when it comes to scaling temperatures and pressures that would be great!

 

[Programmer4]

It does work and I had help with it, but I guess that I just need alot more practice with scaling in general

 

[Ron Beaufort]

be careful what you ask for ... scroll down past the video and download "Scaling" part 1 and part 2 from here ...

http://www.ronbeaufort.com/sample_lessons.htm

but ... to keep it simple, the SCP is probably all that you need with the MLX1500 ...

basic idea: the PID really MUST have its input and output signals scaled from 0 to 16383 in order to give the best results ... anything other than that is just asking for trouble ...

going further ... SOME input and output modules allow you to select "Scaled for PID" ... in that case, your scaling problems are usually over before they begin ...

if the modules do NOT support "Scaled for PID" settings, then the SCP is usually pretty easy to set up ...

as for the PID, there's some other basic information on that same page that might be helpful ...

once again, if you'll post your program we'll take a look ...

gotta go ... little wife needs help planting okra in the garden ...

 

[rwy34ils]

Don't use "Scaled Engineering Units" on the analog output module. I ran into major problems last week. With certain analog output modules, it causes the CPU to fault. I have a previous post about this.

 

[Brijm]

Another thing to remember if you are having any problems with PID, is that by default the noise filter on 1769 analog modules are set to 60 HZ. This value will slow down the scan frequency of the module... Also the number of analog inputs enabled will also add to the scan frequency. If all the inputs are enabled, and set to 60 hz, I believe that this can be up to 0.5 sec. But I would have to double check the manual.