To high measurement time for NI PXI 4132

Hi,
I'm using 4132 to measure very small current of photo transistor device. with 25v source to the DUT it takes me more than 100ms to get an stable current reading.
How will i reduce measurement time?
tnx!

Hi edakoto,
What current levels are you reading? How are you acquiring the data in software?
One thing to try is to reduce the Aperture time of the device. The PXI 4132 defaults to an aperture time of 16.6 ms. You can reduce this using the Configure Aperture Time VI or function. For more information see here:
http://zone.ni.com/reference/en-XX/help/370736F-01/ni_dc_power_supplies_help/4132_aperture/
Thanks
Patrick W.
Applications Engineer
National Instruments

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Oracle related stuff blog:
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SQLTools++ for Oracle (Open source Oracle GUI for Windows):
http://www.sqltools-plusplus.org:7676/
http://sourceforge.net/projects/sqlt-pp/
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Hi there,
I have developed an application to detect interrupts generated by a electronic card and act in consequence. The program has been developed in labview but it calls a dll; that was created with labwindows. The dll is programmed to open the visa communication, enable events and install the interrupt handler and when an interrupt is detected, it reads the value of the different registers of the card and returns it to labview to visualize them.
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Solved!
Go to Solution.

Hello Naity,
First of all, in which thread runs the waiting process? Is it scheduled in another thread than the function setting the flag?
It scheduled in the same thread that I use to configure the communications and configure the card. Anyway, here is the pseudo code of the function interrupt that I programmed under labwindows,.
char* interrupt(void)
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1. Disable some functions of the card to avoid damages.
2. Read registers and put them in a buffer
3. Change the value of flag ---> flag = 1;
In labview, I call the function interrupt with a call library function node (see the capture attached) and the program reads and saves the data from returned from the function.
Secondly, I am not sure this method is the most elegant. You could for example register an event with the function and, insteand of setting a flag to 1, trigger the event and schedule it in another thread (if the function is thread safe). This could reduce your CPU Load even more and seem a bit cleaner to me.
I've never used events before in labwindows but I will try to do it in this way. But anyway, I suppose that I should; somehow, wait the event to occurs in labview while the waiting for the event is programmed inside the dll...and probably the same prompt that i am trying to avoid is going to appear again, because I am not returning the "control" to labview (I mean, labview executes the dll and waits for the event to occur. Then the execution of the labview program is stopped in the call library function node executing the dll)
Third point, which environment of development are you using?
I am working with LV 2010 sp1 and Labwindows cv 10.0.1 and with the real time module.
I did also another test, I divided the program in different functions, one to initialize the communication, another to wait until a interrupt has been detected and the other to obtain the data from the interrupt and close communications. With labview I call first with the call library function node the function to initialize, later I call inside a while loop the wait function like this
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In this way, the prompt appears but after running the application for 10 or 20 minutes and also i checked that there is a time gap between the executions in the loop.
Thanks for your reply and your help,
Jaime
Attachments:
capture.png ‏40 KB

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Dear Ravens,
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Thanks for responding to my question. The annwer for your questions are: Measurment time : 300seconds, Sampling Frequency : 2 Hertz, and Window Type : Hanning. Hope you could hint me on this soon.

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To high measurement time for NI PXI 4132

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