NI USB 6216 and NI cRIO 9022 Data Acquisition

[AmarMakana]

I have worked with NI USB 6216, for a Data Acquisition and Control job. I had to select only the N samples option to work with the Acquisition process. If I selected Continuous Samples option, the hardware responds abruptly to the control signals I give( say I gave a proportional output with respect to the error). In this case, I plotted the acquired waveforms on a chart and I see that the waveforms are displayed with broken lines(like set of samples). I used the DAQ Express VI here in this case. I hope using the low level DAQmx VIs with seperate buffer size allocation, help me overcome this problem. But, I need guidance on how to use it in my case.

Also, I used a NI cRIO 9022 to do the same thing from the same hardware. In this case, I didn't get those breaks in the waveform. I have used the Analog Input Module Channels (like CH0, CH1, CH2 and CH3) and set them in "High Speed" mode for Acquisition. Can anyone tell me why this is happening (breaks in the acquired signal when NI USB 6216 is used but not NI cRIO) ?

And is there a way to avoid those kind of breaks in the signal when I am using NI USB 6216? I think that Buffer Size could be the only reason behind this. but I would like to have a better explaination from a professional engineer who has got more hands on experience than me on these hardware.

I have attached the VIs as seperate files and also their screenshots. Can anyone take a look at these and suggest me a solution?

Amar Makana.

Amar Makana.

[AmarMakana]

I have worked with NI USB 6216, for a Data Acquisition and Control job. I had to select only the N samples option to work with the Acquisition process. If I selected Continuous Samples option, the hardware responds abruptly to the control signals I give( say I gave a proportional output with respect to the error). In this case, I plotted the acquired waveforms on a chart and I see that the waveforms are displayed with broken lines(like set of samples). I used the DAQ Express VI here in this case. I hope using the low level DAQmx VIs with seperate buffer size allocation, help me overcome this problem. But, I need guidance on how to use it in my case.

Also, I used a NI cRIO 9022 to do the same thing from the same hardware. In this case, I didn't get those breaks in the waveform. I have used the Analog Input Module Channels (like CH0, CH1, CH2 and CH3) and set them in "High Speed" mode for Acquisition. Can anyone tell me why this is happening (breaks in the acquired signal when NI USB 6216 is used but not NI cRIO) ?

And is there a way to avoid those kind of breaks in the signal when I am using NI USB 6216? I think that Buffer Size could be the only reason behind this. but I would like to have a better explaination from a professional engineer who has got more hands on experience than me on these hardware.

I have attached the VIs as seperate files and also their screenshots. Can anyone take a look at these and suggest me a solution?

Amar Makana.

Amar Makana.

[KatieC]

Amar, 

What do you mean by the waveforms have broken lines? A screenshot may help clarify. 

However, buffer size is a likely culprit. This KB talks about how the buffer is allocated and gives an example using the lower level VIs you mentioned.  To ease your transition from DAQ Express to the lower level VIs, I would encourage you to look at some of the examples that come with LabVIEW. You can access them by going to help >> find examples. Then select Hardware Input and Output, DAQmx, then Voltage. You can also filter your results for your specific hardware by selecting the hardware in the drop down menu on the bottom left of the example finder and then selecting limit results to hardware. 

Katie

[kabino20989]

Hello Amar,

I am also using cRIO 9022 to control the motor speed. I managed to control the RPM. However, I need to acquire the rpm value while its running (real time).

My questions are:

cRIO is capable of data acquisition?

if yes, could you help me with this?

I am using NI9401 and NI9264 modules, do i need any other ni modules to do data acquisition?

When i was trying to open your vis, it is not opening.

Thanks