on a daqpad 6015, I cannot read voltages other than 5V from AIchannels.

[srdr]

I use a daqpad 6015. I try to apply a sin voltage from the AO0, it doesn't apply. The only voltage I get from the AOs is the constant voltage. I try to connect that constant voltage to one of the AI channels. It always reads 5V whatever the input is-I even connected a signal generator output. USB seems to be working. I have the same problem on two daqpad 6015, so I might be missing something.
Thanks.

[Jennifer O]

Hello srdr,

There are many reasons why you could be seeing this with your cards.  The following questions will help to determine what is causing the problem.

How are you connecting your signals?  What range have you set for your analog input? Are you using Traditional DAQ or DAQmx?  Can you confirm that your analog output works by measuring the signal with another card?  If not, do you have a battery (i.e AA or C) which you can attempt to read?  The DAQPad 6015 has the capability to measure the output by selecting "ao0_vs_aognd" for the analog input channel in the DAQmx test panel.  When the battery is connected, does the card read ~1.5V as expected or still 5V?

You can run the diagnostic utility to test the systems in your card.  Here is a link to one of the utilities:DAQ Diagnostic Utility.  Note that there are different versions of the utility depending on which driver you are using.  The other utilities are linked on this page.

Hope this helps,

Jennifer O.
Applications Engineer
National Instruments

[srdr]

Hi Jennifer,

I use DAqmx-Labview 8.0.

When I use a daq assistant and connect a constant like 2 V as data and 1 sample on demand, I can read that output from AO0 using a multimeter. I change the constant and the value I read changes accordingly.

When I set the configuration fig 1, I got the error message shown.I decreased the frequecy to 4Hz and run it again after sometime I got the second error message (fig2). I cannot read any voltage from output in these processes.

To check if it works with the analog input, I connected a battary of 1.6 V(+ end to AI0 and negative to AIGND-3) I used daq assistant to configure in the first measurement it gave 1.7 V. After stopping and starting again it gave 4.999 and I got the same thing afterwards. If nothing is connected to those pins I get a fluctuating value like 0.6 , 1.8 etc. When I use "ao0_vs_aognd" from the test panel, I got something like fig 4. when try it for the second time voltage value I read the noise changed.

What I want to do is very simple: As shown in fig 3 I would like to apply a voltage to a some resistors from analog output and read one analog input(R1, R2 and Sernsor are resistances).

I used DAQ Diagnostic Utility Version 2.0 for Windows 2000/NT/XP(I use nidaq 8.3) and got the following error message. If I say continue everything seems to pass.


WARNING: It appears that you are attempting to run this utility on a USB device. Due to USB

bandwidth limitations, you may see text failures from buffe overflow and ADC overrun errors.

The use of USB 1.0 or having multiple USB devices connected will increase the likelihood of

these errors/

CAUTION: To test this device, The DAQ Diagnostic Utility writes and reads from various

analog and digital lines. To prevent inadverted operation of external hardware, please

disconnect the cable from Dev2 before continuing.

This untili also performs a device reset on you selected DAQ device. close all other

aplications that access this DAQ device.
Doyou want to continue with the DAq Diagnostic Utility?

[srdr]

...and here is the first figure.
Thank you very much for your time.

[Jennifer O]

Hello srdr,

The first think that I would like to look at since you are able to get static voltages to read out and read in, is the specifications of your device.  Refer to E Series Help (User Manual and Specifications) for more information regarding your device.  The first thing to notice on your device is the maximum output rate is 300S/s.  To get a clean wave you must follow the nyquist theory - the output rate must be at least twice the highest frequency of your wave.  Ideally it will be ten times the frequency or more.  Following this rule, you should be able to output a sine wave with a 30Hz frequency.

Note that if you encounter a DAQmx error the task will stop and you will not see your expected data.

Figure 4 looks like the device is working correctly.  The variation in the signal that you are seeing looks like it can be explained by the resolution of the board with variations of 1/2 the LSB (least significant bit).  Although it is hard to tell due to the scale on the graph.  

To help you resolve the memory underflow error (figure 1) I would need more information about the parameters you set for your waveform and for your output task.  Refer to the E-Series Help linked above for information on the correct locations to connect your signals.  Specifically the Analog Input>>Connecting Analog Input Signals section. I notice in your figure 4 that you are using "differential" mode.  For this mode you will want to connect your signals between AI#+and AI#-.  This corresponds to AI0 and AI8 (pins 1 and 2) for example.  Read through this section to determine if you want to use differential mode or NRSE.

Regards,

Jennifer O.