High Speed 32-Channel Binary Data Logging with DMA Data Transfers, NI 9205 Module

This example demonstrates high speed data logging with CompactRIO. Using this demo, you can log data onto the Compact Flash storage media of the cRIO-900x processor at rates up to 1.5 MBytes/s, which is faster than the maximum speed of the NI 9205 module. Data is transferred from the reconfigurable FPGA chassis directly to processor memory using DMA. Using DMA significantly improves performance and reduces processor usage. The CompactRIO processor reads the data from memory and logs it to disk in binary format. Calibration information is stored in XML format. After running the demo on the CompactRIO cRIO-9004 controller, transfer the data to your computer using FTP. If you use Windows Explorer for file transfer, navigate to Tools>Internet Options>Temporary Internet Files>Settings and check for newer versions on "Every visit to the page."

Then run the Windows application to convert the data to a human-readable LVM text file using the binary data and XML calibration array. Once the data is in LVM format, you can use LabVIEW Express VIs or DIAdem to analyze the results.

Data is transferred to the CompactRIO real-time controller using DMA, and you can set the scan rate and other parameters using normal NI-DAQmx terminology such as "Scan Rate (S/s)." You can also configure the channel settings for each channel of the NI 9205 module, such as whether you want single ended or differential readings and the voltage range (gain) for each channel.

Here is what this example demonstrates:

* Software triggered continuous buffered data acquisition with DMA

* How to use the new NI 9205 module (32-analog inputs with M Series chipset)

* How to set the channel configuration when using the NI 9205 module (terminal mode, voltage range)

* How to control the sample range and buffer size using normal DAQ terminology (Scan Rate, # Scans to Read, Host Buffer Size (Scans), ...)

* How to configure the host memory buffer to be larger than the FPGA buffer and how to start and empty the DMA buffer prior to starting the acquisition

* How to do high speed binary data logging on the cRIO-9004 controller in a time-critical loop

* How to transfer data from the time-critical loop to a lower priority user-interface loop using shared variables

* How to read the NI 9205 calibration data from the module, create a calibration data array for the NI 9205 module and save it in XML format on the cRIO-9004

* How to use RT FIFO shared variables to control the deterministic data logging application without introducing jitter

* How to convert the raw DMA data stream to a 2D array by performing decimation and conversion from U32's to I16's

* How to use the XML calibration data to convert the binary log file to a scaled/calibrated human readable LVM format text file

Requirements

Filename: 4023.zip

Software Requirements

Application Software: LabVIEW Full Development System 8.0
Toolkits and Add-Ons: LabVIEW FPGA Module 8.0, LabVIEW Real-Time Module 8.0
Language(s): LabVIEW

Hardware Requirements

Hardware Group: CompactRIO
Hardware Model: NI 9205, cRIO-9004, NI 9206, NI 9205 D-Sub
Driver: NI-RIO 2.0

Reader Comments | Submit a comment »