[Dsg-hallb_magnets] cernox sensor issue

[Brian Eng]

Instead of explaining with text, which could be confusing, I've attached a few screenshots of the various VI block diagrams.

For reference here's a PDF for the algorithm: M:\hallb_eng\CLAS12\Magnets\Torus\JLab Torus\C&I_Torus\Controls_&_Wiring\Fast DAQ\Cernox Algorithm\TR Algorithm.pdf

Here's what the VI looks like now (attached as current.png):



The issue I've found with the current algorithm is that it will increase the current as the temperature increases, but it won't decrease the current as it goes down.

After noticing that the logic doesn't exactly match the reference algorithm (namely the additional checks on power dissipation) I modified the VI to look like the following (attached as updated.png):



This version properly increased and decreased the current with my admittedly limited testing of using a single potentiometer in place of a cernox sensor and varying it up and down between 4K and 325K.

Finally I removed some of the terminals that weren't being used and changed the code to use more LabVIEW primitives in my process of upgrading to 2016 (attached as simplified.png):


Hopefully the images make sense and get sent through to the mailing list okay.

--
Brian Eng
Detector Support Group
757-269-6018

> On Oct 12, 2016, at 6:44 PM, Amrit Yegneswaran <yeg at jlab.org> wrote:
> 
> hello brian,
> 
> today you and i had a discussion about the cernox sensor problem.
> at the dsg meeting we further discussed the matter.
> you mentioned that there were some errors in the main program VIs, which i'vent seen.
> when you mentioned that you had e-mailed christians (author of the code) and nick i mentioned you to post a few words regarding this issue, so that rather than a select few, all of us including i might be aware of the source and cure.
> perhaps it slipped your mind that i requested you the source and the cure for the problem.
> i am documenting all these issues so that newcomers like pablo and tyler understand these issues and can provide 
> effective support.
> 
> so when you come back on friday please do so.
> amrit
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