National Instruments DAQ X Series User Manual

Chapter 6 Digital I/O
X Series User Manual 6-4 ni.com
an error in this case. With continuous operations, if the user
program does not read data out of the PC buffer fast enough to
keep up with the data transfer, the buffer could reach an overflow
condition, causing an error to be generated.
• Hardware-timed single point (HWTSP)—Typically, HWTSP
operations are used to read single samples at known time intervals.
While buffered operations are optimized for high throughput, HWTSP
operations are optimized for low latency and low jitter. In addition,
HWTSP can notify software if it falls behind hardware. These features
make HWTSP ideal for real time control applications. HWTSP
operations, in conjunction with the wait for next sample clock
function, provide tight synchronization between the software layer and
the hardware layer. Refer to the NI Developer Zone document,
NI-DAQmx Hardware-Timed Single Point Lateness Checking, for
more information. To access this document, go to
ni.com/info and
enter the Info Code
daqhwtsp.
Note (NI USB-634x/635x/636x Devices) X Series USB devices do not support
hardware-timed single point (HWTSP) operations.
Digital Input Triggering
Digital input supports three different triggering actions:
• Start trigger
• Reference trigger
•Pause trigger
Refer to the DI Start Trigger Signal, DI Reference Trigger Signal, and
DI Pause Trigger Signal sections for information about these triggers.
An analog or digital trigger can initiate these actions. All X Series devices
support digital triggering, but some do not support analog triggering. To
find your device triggering options, refer to the specifications document for
your device.
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National Instruments DAQ X Series Specifications

General

Brand	National Instruments
Model	DAQ X Series
Category	I/O Systems
Language	English