Chapter 2
Using Your NI 653X
2-16
ni.com
Figure 2-9.
Programming Pattern I/O in NI-DAQ LabVIEW/LabVIEW RT API
Notes
If you are using an external clock for finite pattern input, the NI 653
X
requires an
extra clock edge to move data from the DIO ASIC and into the computer memory after the
final data sample is acquired.
If you are performing a finite pattern output operation, you can call DIO Wait VI instead
of the DIO Write VI after the DIO Start VI. For more information about these VIs, refer to
the
LabVIEW Help.
♦
NI PCI/PXI-6534
For output buffered transfers the NI 6534 by default preloads the onboard
memory with data before starting the output operation. Preloading
eliminates or reduces the impact of the PCI bus bandwidth limitations and
increases the overall transfer rate. The preloading process causes a small
delay between the start command in software and the actual start of data
transfer. If this is a concern, you can disable the preloading by calling the
following function/VI before the software start command:
•
NI-DAQ C interface—In the
Set_DAQ_Device_Info
function,
set the
ND_FIFO_TRANSFER_COUNT
to
ND_NONE
.
•
LabVIEW—Use the DIO Parameter VI to set the
Scarabs Preload
Enable
attribute to
None
.
Trigger?
Done?
DIO Read/Write VI
DIO Start VI
DIO Clear VI
No
Yes
Yes
No
DIO Config VI
Write?
DIO Write VI
No
Yes
Trigger?
No
Digital Trigger Config VI
Digital Trigger Config VI
Yes
Содержание NI 653 Series
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