©
National Instruments Corporation
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6711/6713/6715 User Manual
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Common Questions
This appendix contains a list of commonly asked questions and their
answers relating to usage and special features of your 671X device.
General Information
What is the 671X device?
The 671X device is a switchless and jumperless analog output device that
uses the DAQ-STC for timing.
What is the DAQ-STC?
The DAQ-STC is the system timing control application-specific integrated
circuit (ASIC) designed by National Instruments and is the backbone of the
6711/6713 device. The DAQ-STC contains seven 24-bit counters and three
16-bit counters. The counters are divided into the following three groups:
•
Analog input—two 24-bit, two 16-bit counters (not used on
6711/6713)
•
Analog output—three 24-bit, one 16-bit counters
•
General-purpose counter/timer functions—two 24-bit counters
The groups can be configured independently with timing resolutions of
50 ns or 10 µs. With the DAQ-STC, you can interconnect a wide variety of
internal timing signals to other internal blocks. The interconnection scheme
is quite flexible and completely software configurable. New capabilities
such as buffered pulse generation, and seamlessly changing the sampling
rate are possible.
What does update rate mean to me?
It means that this is the fastest you can output data from your device and
still achieve accurate results. The 6711/6713 device has an update rate of
1 MS/s at up to 4 channels, and the DAQCard-6715 device has an update
rate of 1 MS/s on 1 channel and 480 kS/s on all eight channels
simultaneously. However, the outputs of the DAQCard-6715 settle to
within ±1/2 LSB of their final value within about 5 µs, restricting
large-scale accurate outputs to 200 kS/s/channel.
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