USB 6009 Hangs

[DevDeptMartin]

Hi,

I'm running long term tests (2 days) using the USB 6009 DAQ. My problem is that the application will work fine for about 20 mins - 1 hour, then for no apparent reason freeze for 30 seconds or so before carrying on as if nothing happened!

I am using a Dual-core laptop and have turned off all the standby etc, settings in the windows control panel, and upped the prioty of LabView in task manager but it still happens.

Any ideas anyone?

[Mark M]

Hi there,

Hope you are well today!

Can you confirm for me please if you have enough disk space left before and after say 20 mins of acquisition? What is your sampling rate?

It appeared to me that some applications or hardware were trying to interrupt the OS at some point. It would be great if you would have a clean install of the OS with only NI software to test it again.

[DevDeptMartin]

Hi,

Thanks for your response.

The PC is only a month old so it isn't clogged up with lots of programs, just Windows XP and LabView really.

I have 74Gb of free disk space and have set the 6009 to 1-sample on demand. I don't know how many samples this is per second?

Hope this helps...

[Mark M]

Hi,

If you set it to 1-sample on demand mode, the sampling rate will have to be explicitly controlled by your software, e.g a looping structure which I guess you are using? Do you have a wait function inside your loop? This will determine the actual sampling rate.

The on demand mode is only suitable if you are acquiring data with a rate of say every 500 ms or 1 second.  If you intend to use a sampling rate in the range of kHz or 10s of kHz, you will need to use acquire N samples mode or acquire continuously so your USB-6009 can take advantage of the onboard FIFO buffer, rather than transferring data across the whole PC bus 10000 times in a second, the overhead and latency will be huge.

Hope this helps,

[DevDeptMartin]

I'm running a state machine, on the states where data is being acquired I have a 5ms loop delay. I'm only reading in 1 analog reading throughout the program.

Does the USB 6009 have a data buffer? I didn't think it did?

[Mark M]

Hi,

Do you have any other delay functions in other states? Could you explain more about your application please? I am not sure which acquisition mode would suit you better.

At this point, I do not have any confident to say at exactly which part on your system can cause this interruption. I can only suggest you to disable as many background services/process you are running on your Windows XP as this does not appear to be a fault in the USB-6009 itself, but more likely caused by some process, the LabVIEW program, the OS or chipset drivers.

Do you have any other PC that you have access to? I recommend you testing your LabVIEW program on another machine.

Yes, the USB-6009 has a 512 bytes onboard FIFO buffer.

Datasheet of USB-6009

[DevDeptMartin]

Hi,

No the other states just activate certain digital outputs on the 6009. The application controls a pneumatic actuator via some soliniods, the postion of the actuator is fed back to LabView by a pot (which is being sampled by the 6009).

The actuator moves quite slowly and I could probvally get away with sampling it at a lower rate, maybe 20 - 50Hz.

Thanks.

[Mark M]

Hi,

Please try to increase the 5 ms wait time while looking for some process/services you can disable in Windows and then run it again to see if it exhibits the same behaviour.

Also, do you have any anti-virus program that you can disable?