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AI Sample Clock Timebase Signal
The AI Sample Clock Timebase signal is divided down to provide a source for Sample Clock.
AI Start Trigger Signal
Use the Start Trigger signal to begin a measurement acquisition. A measurement acquisition
consists of one or more samples. If you do not use triggers, begin a measurement with a
software command. Once the acquisition begins, configure the acquisition to stop in one of the
following ways:
•
In finite mode, when a certain number of points has been sampled
•
In continuous mode, with a software command
You can specify a default delay from the Start Trigger to the first sample.
Use the Start Trigger signal with a time source, by specifying a specific time in NI-DAQmx.
Refer to the
Time Triggering
topic in the
NI-DAQmx Help
for more information on accessing
time-based features in the NI-DAQmx API.
Analog Input Sync Pulse
You can use time as a trigger for sync pulses on the FieldDAQ device. To use a sync pulse
with a time source, specify a specific time in NI-DAQmx. Refer to the
Time Triggering
topic
in the
NI-DAQmx Help
for more information on accessing time-based features in the
NI-DAQmx API.
Note
To accurately synchronize Delta-Sigma devices in two or more separate
tasks, you must specify the same sync pulse. Otherwise, a sync pulse is initiated by
software implicitly, even if time start triggers are specified for the tasks. However,
for multidevice tasks, the sync pulses and start triggers are automatically
synchronized.
Time-Based Triggers
FieldDAQ devices feature automatic network-based synchronization with compatible
networks and IEEE 802.1AS-capable NI Linux Real-Time controllers. The SYNC logo on the
device front panel indicates that the device is capable of hardware-based synchronization over
a network.
FieldDAQ devices can be daisy-chained together or connected to external networks that
support IEEE 802.1AS synchronization, and all device timebases will be automatically
synchronized. Refer to
Synchronization across a Network
for more information about
supported topologies and other technical requirements.
Network-synchronized devices can also take advantage of time-based synchronization features
in NI-DAQmx. Certain triggers can be specified in terms of time of day. Time-based triggers
and multidevice tasks (spanning multiple network-synchronized FieldDAQ devices) can help
simplify programming for large systems.
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FD-11634 User Guide