5681 SFP works, VI's do not.

[Hepcat]

I have an NI-5681.  Here are the scope settings I'm using.

Scope Mode:

Capture time 1.5

data points 200

Gate start .1

Gate end .7

General Settings:

freq 2.39Ghz

Average method moving

Averages 128

offset 20

range auto

Trigger:

internal

auto

Level 0

Edge Positive

delay 0

Noise immunity 10

I've tried to recreate this measurement using the VI's (attached).

It worked until the "Read Scope Data.vi"  Then it says response was invalid.  I can't get the exact error because the sensor stopped working on my system.  I've heard there is a beta driver that may fix the "No Sensor" issue, how can I get it?  That issue aside why doesn't the read work?  Also, there are a lot of vi's on the palette, is there any perferred order to connect them?

Thanks for any help,

Chris

[JohnFenner]

Hi Chris,

I can probably help you with this.  Can you attach the VI or a screen shot so I can see what we're working with?

[Hepcat]

If the attachment shows up, it was on the first post as well.

[JohnFenner]

Hey Chris,

I'm digging into your issue today.  I can reproduce your error in 1.1, and it's a new bug to me.  I have a pretty good idea what's going on, but I need to put a little more due diligence into understanding it, before I can say it's for sure fixed in 1.2.  If you email me directly (my email is on my profile), I'll get back to you when I have a beta build with the fix in it.  Sorry for the inconvenience.

[Hepcat]

I installed the beta driver and now the Read is timing out.  It's set to 45 seconds

-1074126816

ni568x Read Scope Data.vi<ERR>Maximum timeout exceeded before operation could complete

[JohnFenner]

Hi Chris,

I think the problem boils down to the setting for auto average count.  In Scope Mode, average count is the number of times that we expect to receive a trigger and collect a record, 128 times in this case.  Those 128 records are averaged to give us a single record with 200 data points.  Your RF signal has to have 128 rising edges within the timeout or else the read will fail.  I am attaching an edited version of your VI with more extensive notes.  Let me know if this doesn't help.

[Hepcat]

I tried 128 averages, 1 average and skipping the configure averages step altogether, all resulted in a time out.  I also added a zeroing step to the front.  VI attached.

[Hepcat]

Got it working, it was the trigger level.  The soft front panel appears to apply the offset to the trigger level.  But the VI's do not.  So if you attempt to use the exact same settings you used on the SFP, it may not trigger, unless your offset was 0.

Thanks for all your help!

[JohnFenner]

That's great news!

[Hepcat]

How do you determine if it's nessasary to to zero the sensor?  The "ni568x Is Zero Correction Complete (VI)" will tell me if the zero is complete or not, but I don't know how to tell if it needs to be zero'd or not.  Does it need to be zero'd everytime before I use it?