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Veristand 2011 RT and SCXI-1540 problems

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Good afternoon,

    As in the subject we are having problems with our SCXI-1540 card which we use for acquiring a mixed selection of RVDTs and Resolvers.

Specifically we are running our setup with Veristand 2011 on a RT target which has a custom device to control the SCXI card via a PXI-1050 chassis and PXI-6221 card, everything is just fine but every now and then the 1540 card suddenly start showing a rolling angle measurement for the resolvers.

By checking with an oscilloscope the resolvers inputs are fine but we notice that when the event happens the excitation somehow switches from the set 5KHz to 10KHz and that even by undeploying and redeploying the project and verifying that the DAQmx Channel property node used to set the excitation frequency has the correct setting of 5KHz and does not return an error, there is no way of getting the channel back to 5KHz and it stays stuck to 10Khz. The only way to be able to control the excitation frequency again is through a full power-cycle of the RT/Chassis.

 

We also verified by adding some debug code in the custom device that on the event either the sin channel or the cos channel starts showing a rolling voltage measurement thus our angle measurement starts rolling too.

 

So far this behavior seems to have shown only with resolvers as we have been mostly testing those and we sync excitation between a sin/cos pair.

 

Please advise

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Hi,

 

did you make some tests outside Veristand only using LabVIEW ? Are you seeing the same behavior ?

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We do not have the capability to do testing on LV right now (mostly logistics limitations).

By the way it seems to be related to some susceptibility of the card to EMI, we have a few 1Amp lines and relays very close to the card bulkhead and we found out that when switching those line on and off usually the card starts showing this behavior within 10 to 20 switching.

I just hopen somebody had the problem and maybe replied. I'm on with NI Germany support to see what comes next, it's either a faulty card, or really we need to make further way between the SCXI-1540 cables and bulkhead and the 1A lines.

 

cheers

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Hello Claudio,

 

so have you already created a Service Request with NI Germany?

 

Regards

Anoj Mubarak
National Instruments
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Yes,

   I opened this topic on the forum as when I sent the email to the germany support I got an automated response saying that the reference number was missing or something like that so I thought my email was discarded. I'll update this topic as soon as we get to a solution so the pulic might find useful information.

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Solution
Accepted by topic author Claudio_G

I just noticed I never gave a solution for this.

The problem was flyback current from another system causing EMI glitches on the Resolvers lines somehow messing up with the 1540 card which basically stopped decoding the resoulvers input correctly, I added a reset in the custom device close case and that fixed the not being able to get out of the 10Khz excitation on redeploy. The final fix however had been adding flyback diodes to the high power system tokill the glitches. So beware your setup as SCXI-1540 cards seems to be sensitive to such events.

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