Can I Buffer I/O Data While in Scan Mode? 

Updated Apr 30, 2018

Reported In

Software

  • LabVIEW FPGA Module
  • LabVIEW Real-Time Module

Issue Details

I have a timed loop on my controller that reads data provided by the scan engine. I would like to read more than a single value per iteration without losing any data. Can I buffer I/O data while in scan mode?

Solution

You cannot buffer data while in scan mode. To avoid losing data when accessing I/O variables locally, you must read each data point before the next point arrives and avoid writing data faster than the NI Scan Engine period.

If you really need a buffer, you should disable scan mode and enable the LabVIEW FPGA interface and implement the buffer on the FPGA. 

Additional Information

National Instruments recommends implementing Direct Memory Access (DMA) FIFO to transfer buffered data between a host and an FPGA target (see ​How DMA Transfers Work (FPGA Module)).
 

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