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Measurement not following graph

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Measurement not following graph

Postby rocketcaver » Wed Feb 03, 2010 8:30 pm

I use an ADC42 on an old Win98m computer to monitor a very slow DC pulse, aprox .5 to 1hz.
This is the voltage of a charging and discharging capacitor under test. I watch the cap charge and discharge several times through a load, then switch the device off and watch the cap discharge through the bleed resistors.
Peak voltage is about 1060 volts DC. (I am using a voltage divider network to allow this high voltage use)
Chart recorder mode works best for my use.
I use the O and X cursers to form a "window" of acceptability, as long as the peak stays within the window everything is good.
I would like to also display the actual DC voltage, but running a meter display along with the scope display either seperatly or in composit mode slows everything down to the point of being useless. I have therefore tried using the "Measurements" feature on the scope screen, but with unsatisfactory results.
When using the "DC Voltage" and "Whole Trace" settings the voltage reading does not follow the scope graph at all.
While the graph shows the peak at 1060 volts, the DC voltage will only read around 600 volts or so. Then when power is shut off the voltage reading stays at several hundred volts while the graph shows the cap slowly discharging down to around a hundred volts or so. Then the DC voltage reading suddenly "wakes up" and starts to slowly fall and will eventually get down near zero, but long after the scope graph. Using the "Peak to Peak" setting shows the peak voltage better, but then acts even worse when the power to the device is turned off and the bleed resistor discharge cycle is being viewed. I have tried many different settings, but nothing seems to help.
Can you make some suggestions?
My software version is 5.13.4 - 32bit
Thank you.
rocketcaver
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Re: Measurement not following graph

Postby rocketcaver » Thu Feb 11, 2010 10:48 pm

No help here?
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Re: Measurement not following graph

Postby PeterF » Fri Feb 19, 2010 2:31 pm

Hi,
Your set-up is so old it is difficult to reproduce it here. To start with, please update your software to version R5.16.2 which is what we recommend for Windows 98. Please contact on Help-desk if you still have problems:-
support@picotech.com
Regards,
PeterF.
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Re: Measurement not following graph

Postby rocketcaver » Fri Feb 19, 2010 5:21 pm

Thank you for your advice.
I installed the newer version as you suggested.
It will open my testing files generated by my older version but the X and O cursers do not appear. When I try to recreate them the program crashes.
It looks like the new installation re-wrote the old installation, so I cannot fall back to the old version.
Now I have no choice but to recreate all of my tests since they all cause the program to crash.
Thanks for your help.
rocketcaver
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Re: Measurement not following graph

Postby PeterF » Mon Feb 22, 2010 10:48 am

Hi,
I am sorry you are having difficulty.
Please could you send a few short files made using your original program so I can see your exact problem and if we can do anything about it.
Please send to my personal email:-
pfrench@picotech.com
Regards,
PeterF.
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Re: Measurement not following graph

Postby rocketcaver » Mon Feb 22, 2010 3:59 pm

I rebuilt all my tests so they now work on the newer version, it didn't take all that long was just a nuisance.
It seems to act the same though with the meter and measurement functions.
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