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keklon

Multiple PID Loops

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I have an application where I will run 6 separate PID Heating loops with a Vision series V130-33-T2 controller. I have watched and understand the tutorial listed for setting up the PID parameters in regard to Autotune FB's. My question,  what is the best practice for running A-tune on multiple loops? Should each have its own sub program? How can be accomplished on the first scan? I have searched and found only single loop examples. Can someone  please point me in the right direction.

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It is easier for writing and debugging if you make a subroutine for each PID and then call them from the main. What do you mean by first scan? If you ask about "Config Blocks" you can put each one in those separate subroutines, it's convenient to have it there because it shows input, output, set point and status at a glance in online mode. Be sure to call config over SB2 startup bit.

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"first scan" I was referring to SB2 for the config blocks.

I am writing the program now and am sure to have more questions as I get further along.

Thanks for the input.

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4 hours ago, keklon said:

"first scan" I was referring to SB2 for the config blocks.

SB 2 will activate any ladder rung it's placed in on first scan, no matter where (as long as it's called). It doesn't have to be the Main Routine.

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I have written a program running 24 PID loops which worked fine.  You do have to provide a separate memory allocation for all the MI's (including the auto-tuners) for each one.

Post your program so we can have a look.

Joe T.

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For troubleshooting I find it most convenient to have all the  PID configuration blocks all tied together on top of the main Ladder routine. 

  I am unable to view the HSO in hardware configuration for beyond Output5. The spin button does not cycle this low. The only way I was able to enter the values was to start at O5 and enter the data moving toward O1- O0. Is there another window  to maximize the entry fields? I think I may have doubled some MI's. Other than this I am having success, i was able to perform an Atune on one of my loops now I am trying to set the program up to run all 6 loops at startup and also have an option to one a separate A-tune as needed.

OrSolder36_DialAutoTuneSelect.vlp

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11 hours ago, keklon said:

I am unable to view the HSO in hardware configuration for beyond Output5. The spin button does not cycle this low. The only way I was able to enter the values was to start at O5 and enter the data moving toward O1- O0. Is there another window  to maximize the entry fields?

Is there no scroll bar on the right? What version are you using?

snip.PNG.10420fd0d194e7f8d7dd426e9feceabf.PNG

I think "Run PID" function blocks shouldn't be called over transition contact. Net 11 "A-Tune" subroutine.

Why are you autotuning on every startup?

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I see that you are able to view all the HSO settings. I am using V 9.8.79 Build 0 BETA. Should I try the last not beta version ? What version is the one from in the screen shot above.? I cant move scroll bar any lower.  See pic.Visilogic.thumb.PNG.489264629f32d5d1f8a28f96c15912ee.PNG

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+1 to what Flex says.....

This beta version seems to be a big problem lately,

it's great that the beta is available for seasoned users to experiment with and help find bugs, but we are seeing too many new users grabbing the beta version for their first programming experience....

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Thanks for the tips.

I unknowingly downloaded this BETA version. I recently upgraded my laptop and the IT department here where I work loaded the program. I will now request the non BETA version.

I realize that I do not need to run an auto-tune on every startup. 

The Auto tune did a good calculation for parameters to run at 300 degree F but when i raised to the desired 800 F It needs to be re-tuned. The A tune wont seem to help for the higher temp.

The temperature overshoots 10- 17 degrees. 

What is the best method for correcting overshoot on a PID loop? any thoughts? 

 

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I perform manual tuning when I have temperature process instead of auto tuning. I have better performance.  In general, to reduce overshoot, decrease P, but all systems have their own behavior.

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I  need to have  some safeguards in place for the case of an open TC. When the Thermocouple is unplugged the  HSO is driven 100%. I see an red indicator appear on the IO-ATC8 . Is this reported to the control in a SB or do I need to write a net and do a range comparison with upper and lower limits?

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In case you all haven't noticed, the download site has been changed recently.  So thanks @Cara Bereck Levy, for persuading the powers that be.  I'd still be not showing the beta at all, as it seems that Youngies ALWAYS have to have the latest and greatest!  But this is much better than the previous situation.

cheers, Aus

newdownload.thumb.jpg.7ea64dbb84b4299920959ece66956e48.jpg

 

 

 

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21 hours ago, keklon said:

I  need to have  some safeguards in place for the case of an open TC. When the Thermocouple is unplugged the  HSO is driven 100%. I see an red indicator appear on the IO-ATC8 . Is this reported to the control in a SB or do I need to write a net and do a range comparison with upper and lower limits?

Take a look to the module specs. It shows register values when analog input is out of range.

https://myzone-kza3sadj.netdna-ssl.com/wp-content/uploads/2015/12/IO-ATC8.pdf

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On 3/20/2019 at 2:14 AM, Ausman said:

In case you all haven't noticed, the download site has been changed recently.  So thanks @Cara Bereck Levy, for persuading the powers that be.  I'd still be not showing the beta at all, as it seems that Youngies ALWAYS have to have the latest and greatest!  But this is much better than the previous situation.

Took a little time--but yes :)

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