Choosing Dma Or Interrupt Transfers; Connecting Signals; Creating A Program - National Instruments 653X User Manual

High-speed digital i/o devices for pci, pxi, compactpci, at, eisa, and pcmcia bus systems
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Connecting Signals

Creating a Program

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Choosing DMA or Interrupt Transfers

When using DMA (by default), the 6534 device transfers data in 32-byte
blocks and the 6533 device transfers data in 4 byte blocks. Therefore, at any
time during a continuous operation, there may be up to 31 bytes (or 3 bytes
for 6533 devices) of data in an internal device FIFO. You can use interrupt
driven transfers if you need to retrieve data immediately as it is acquired.
Interrupt driven transfers are slower and take more processing time from
the computer than DMA driven transfers.
Connect digital input signals to the I/O connector using the pinout
diagrams, Figures C-1,
68-to-50-Pin Adapter Pin
If you are using external start and/or stop triggers, connect to the
appropriate pins—start trigger (ACK or STARTTRIG) and/or stop trigger
(STOPTRIG).
Using the following flowcharts as a guide, create a program to perform
change detection. Figure 2-21 and 2-22 display flowcharts for C
programming using NI-DAQ, while Figure 2-22 shows a LabVIEW
programming flowchart.
The boxes represent function names for the appropriate software, and the
diamonds represent decision points.
653X I/O Connector 68-Pin
Assignments.
2-31
Chapter 2
Using Your 653X
Assignments, or C-2,
653X User Manual

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