Fast readings with high range

[Gazlar]

I have been part of a team that has built a tester capable of doing an in circuit test on one of our products. At the moment it is very slow and I am just trying to find way of squeezing more speed out of the tester.

Lets just take the resistors. I am using a NI 4072 DMM.

I have grouped resitors into groups of similar values so I am not changing the range to much but even so it takes 15 seconds to test all the resistors.

So after taking some advice about other matters that I posted on here, I ran some experiments.

First I see the DMM to do multipoint and software trigger. I also changed the digits down to 3.5.

Now if I set the DMM to a range of say 10k and left that fixed, despite higher components reading NAN I could blitz all resistors in 1.06 seconds.
If I then fix the range to say 10Meg to read the larger resisters then the test takes about 8 seconds..... clearly the range has an effect.

So my question is, is there anyway I can speed up what I am doing in terms of reading larger valued components? largest value is about 1 meg and lowest is 100Ohms
Or
Is there some other PXI card that I can buy that would be better is I am after speed?

[gavinhill]

Hi Gazlar,

I think that the reason for the time difference in your testing is due to the intrinsic physical restrictions of measuring resistance. The settling time, and hence test time, is a function of resistance value and as such the higher the resistance of the DUT the higher the measurement time. This is more fully explained here and here. 

As far as I am aware switching to a different DMM will not reduce the test time in the manner that you wish. 

I hope this helps to understand the issue. Let me know how you get on. 

Happy Holidays,

Gavin

[Gazlar]

Thanks for the repoonse.

I only asked because my team are trying to get the compoany to build in house test equipment rather than buy from an outside source.
We managed to convince them to allow us to build a tester which was almost half the cost of purchasing one.

Anyway, we have an ATE that is 10 years old and i'm just curious on how it can do a full Incircuit test in 5 seconds! That includeds resistors, capacitors, diodes, transistors etc.

[Dennis_Knutson]

What piece of ate are you trying to replace? Most use custom hardware and firmware and not an off-the-shelf dmm. Do you have the schematics of the ate you are replacing? You can certainly duplicate the functionality but duplicating the utility on the cheap will be difficult.