6218 green light blinks twice rapidly. what does this mean?

[topaz]

I am using a USB-6218.  Over the weekend, it shut itself off twice - loss of green light and data recording capabilities.  It is now working, but the green indicator light is blinking twice very fast, with a pause, and then repeats.  What does this mean?  I can't find it in the user manual.

[topaz]

Update:  I connected the device to a new computer, and it didn't blink twice.  Thinking I had solved some problem with firmware, I reconnected it to the original computer and it is back to blinking twice.  Please help!

[MickeyD]

Hello,

The double blink of the green light implies that it is connected to a USB full speed port, instead of a USB Hi speed port.  This is noted on page four of appendix A in the manual.  The main result of this will be that your maximum sampling rate will be lower than if you had a Hi speed port.  When you install it on the other PC you see a single blink.  Do you know for sure that both PCs are running identical versions of your operating system.  If you think that the PCs should behave the same please let me know what version of DAQmx you are using and what your operating system is.  The other thing I would advise you to check is to look at the setup in Measurement and Automation Explorer and make sure that the device appears under DAQmx device on both systems. Please let me know if you need further help with getting your USB device to work as expected.

Have a great day,

Michael

Applications Engineering
National Instruments

Message Edited by MickeyD on 12-05-2006 03:30 PM

[kjhlkjljkh]

Take a look at pages A-3 and A-4 of the User Manual:  http://www.ni.com/pdf/manuals/371931a.pdf

A single-blink means that the device is operating normal in a USB Hi-Speed port.  A Double-blick means that the device is connected to a full-speed port.

The USB-6218 will still operate when connected to a full speed USB port, however, you will not be able to go at the full AI/AO/CTR rates because of limited USB bandwidth.

[topaz]

Thank you for your help.  Both computers have USB 1.1 ports, are running windows XP, and use DAQmx V 8.3.  It doesn't make sense to me that one computer would work and the other wouldn't.  I believe that there used to be a single blink when the device was attached to the computer that now causes it to double blink. 

[MickeyD]

Hello,

I would recommend doing a couple troubleshooting steps.  Make sure the device passes self test.  Also, if measurement and automation explorer (MAX) is open, does the device appear under NI DAQmx devices on both computers.  When you say the device lost power twice over the weekend was the device losing power or did the whole system lose power?  When the device double blinks are you seeing different behavior than when it single blinks.  You could test this out by simply opening the test panels in MAX and seeing what rate you could read at before it returns a buffer overflow error.  See if this value is the same on both systems.  It seems that your device would double blink on both systems, but lets find out if there is a different performance.

Have a great day,

Michael D
Applications Engineering
National Instruments

[topaz]

The device passes the self test on both systems, and shows up on both under NI DAQmx.  The device was the only thing losing power, not the computer.  I just came in and found the light was not illuminated and no data was recording.  I have no tried to read at the highest rate possible until a buffer overflow error occurs...I am not sure that I know how to do this.  Is it just changing the sampling frequency?  I think its set at 1K now.  One odd change in performance that I did note is that after I noticed the double blink, my measured values were slightly lower than they should have been.  So I played around with sampling rates and number of data points taken, and that seemed to fix the slightly low values.  And then I put it back to the high value of 1000 samples at 1k Hz, and the values remained unchanged (so they were still correct).  This whole situation is just very puzzling to me.   

[topaz]

Ok, I opened Measurement and Automation on each computer and created a task to test the sampling rate on both.  On both systems I was able to sample continuously at a setting of 1000 samples at 250k HZ sampling rate.  When i upped it to 260k HZ, both systems said the rate exceeded what the ADC was capable of.  I still have the double blink on one and not on the other. 

[MickeyD]

Hi,

Seems like the cards are sampling at the max rate.  now try and make the buffer the choke point, once you have 250 kHZ set decrease the number of samples.  See if they both create buffer overflow errors at the same point.  If they do, then the devices are performing the same.  At that point I would suggest trying to reset the DAQmx configuration in MAX on the machine causing two blinks.  You can do that by going to Tools » NI DAQmx Configuration » Reset NI DAQmx Configuration.  If you are still seeing the same behavior we could try switching the USB driver to see if that will reset the blink.  Tools » NI DAQmx Configuration » NI DAQmx USB Driver Selector. set it to the VISA, then restart the computer switch it back and restart again.  If none of that changes the blink characteristics then I would suggest reinstalling the drivers.  You would uninstall DAQmx then reinstall it.  If you are seeing the exact same behavior from the test panels though I would not recommend spending too much time trying to get rid of the blink.  Please let me know if you need further information on this issue.

Have a great weekend,

Michael D
Applications Engineering
National Instruments