DAQ6510 OverflowHz/V Issue

Hi,

I'm using daq6510 with multiplexer card 7701, I'm measuring CH16 (pins 11,44) in 50pin connector cable.

When using regular fluke model 179 / model 289, I see 19.23Hz in frequancy mode (ACV Frequancy).

With fluke - If I'm putting range 600mV I see the 19.23Hz and If I'm going over to 6v,60v,600v,1000v it shows 0Hz.

WIth daq6510 - I'm putting range 100mV i see OverflowHz, 1V i see OverFlowHz, 10v i see 0Hz and so on...

My issue is that i cannot measure with daq6510 this frequancy.

Does anyone encountered this type of issue? What do you suggest do about it?

Thanks in advance,

Maxim

I forgot to mention the voltage reading with fluke its around 400mV, it seems overflowed but fluke shows it.
Can I still show it on DAQ6510 even if its overflowed? :(

if you put known DC on the channel, does DCV read it correctly?

For the AC signal, can you close the channel and use the Digitize V function on the signal?
You can slow the digitizer to 1KHz sample rate and auto aperture to get boxcar average from 1MHz digitizer.
What does that think you signal looks like?

Hi Andrea!
First off, thanks for replying.
Second,
Can you explain or point me where in the manual I can use the Digitize V function on the signal? the signal is at channel 116 so how should I measure digitize V on it without it being enabled? (I tried to measure using front panel and the results are the same if that's what you ment)

How I slow the digitizer to 1Khz sample rate and enable auto aperture? I need to measure channel 116 .

One thing i can say is that If i'm using detector bandwidth of 300hz I can measure 1v range but its jumping from overflow to some reading, I hertz I put the aperture to 2ms and it does the same but the measured hz is still 0. I need to measure 19.2h at milivolts and not volts for some reason.
 

By the way the first question about DCV channel, even if there is some reading, will it help? I need the 19.2hz FACV reading :)

My question about using DCV was to get some confidence of the relay function and the wiring to it.

To make it simpler, do select front terminals and directly feed your signal to dmm.

For the digitize V, same place you select ACV or DCV, pick Digitize V.

Swipe screen to see the digitize settings for sample rate and number of samples.

For your ~20Hz signal, I’d say slow down the sampling rate and set buffer size.

1KHz and 1000 samples = 1 second of data

Swipe to graph.

What range do you have to use to reliably see the waveform?

What does waveform look like?  Hoping it gives some insight into why VAC is having trouble.

For freq measurements, what aperture setting did you use?  A 2msec aperture is not long enough to measure freq or period of a 20Hz signal.

Hi Andrea!
Once again thanks for replying and Explaining further,
Please see attached files (images). We went and set to digitize V, tried sample rate at 1000, count at 10000.
You can see how the waveform looks like, We tried different options but at the end we need a freq reading..
We tried a 30msec aperture and the device did some constant switch button noise and somehow showed 15 times 0 and 2 times 19.2hz and so on... it seems like it almost somehow reads it but then again with other devices like fluke I get constant freq on mV ac, and here overflowed!

Bottom line,
This 30msec is a temporary fix, It's not ideal. Is there a way to work around a overflow protection? 
Or set the device to work on other ranges? It's a bit frustrating..

- Attached Images here -

Thank you for posting the screenshots.

So clearly there are some crest factor issues as you have a significant leading edge spike in the waveform.

In the digitizer mode, if you up range the voltage, what is the max voltage of the spike?  On the full screen graph, you can zoom in and place cursors too.

I suspect that when using the Freq or VAC modes and low ranges, the spike is saturating the range.

But higher ranges that tolerate the spike, don’t have sensitivity for the much lower amplitude remaining signal.

Not sure the origin of the spike.  Calm it down if you can (reduce inductance if the spike corresponds to current load changes).

With TSP and Digitize, you could extract the freq info from timestamps between two peaks for example.

Can your use case support idea of not scanning conventionally, but closing a channel and then calling a TSP function?

Here is a little more general info on using the Digitize Voltage and the TSP scripting to extract frequency information from a measured voltage waveform.

For your waveform frequency and amplitude, configure the digitizer to obtain enough data to capture at least two peaks.


In attached document, is more info and a sample TSP script.

Hi Andrea!
The max voltage of the spike is around 3.3v, I think other measuring equipments just ignoring this peak when using mode 'milivolt'.
I will try the last information you've sent about measuring using Digitized and TSP, I'm doing this using matlab.

I must say that I came here not to get help on fixing the signal since my company have engineers to do so. It's time consuming ($$) and I thought there is a workaround for this 'overflow' situation.. I need a reading similar to cheap 200$ measuring equipment :)
Would be nice in next firmware versions to implement a way to ignore spikes (overflow)...

Thanks, 
I will update if you helped and close the thread if it did.

Hi,
I have an update!
Your last reply Andrea was excellent! I managed to make a perfect measurements,  Collected successfully the frequency.
This is a great solution, hopefully it holds water for long time.

One thing to notice for those who read this and in trouble too:
1. The PDF contain example for front measurement (without specific channel) you need to adjust it accordingly if using channels setup.
2. I had an issue with debug mode (breakpoints) so be prepared to use print('test1..etc') for debugging.

Good luck,
Thanks again for the help!