Chapter 3
Using the NI PXI-4204
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National Instruments Corporation
3-7
Timing and Control Functional Overview
The NI PXI-4204 is based on the NI E Series DAQ device architecture.
This architecture uses the NI data acquisition system timing controller
(DAQ-STC) for time-related functions. The DAQ-STC consists of two
timing groups that control AI and general-purpose counter/timer functions.
These groups include a total of seven 24-bit and three 16-bit counters and
a maximum timing resolution of 50 ns. The DAQ-STC makes possible
applications such as equivalent time sampling, and seamless changing of
the sampling rate.
The NI PXI-4204 uses the PXI trigger bus to easily synchronize several
measurement functions to a common trigger or timing event. The PXI
trigger bus is connected through the rear signal connector to the PXI chassis
backplane. The DAQ-STC provides a flexible interface for connecting
timing signals to other devices or external circuitry. The NI PXI-4204 uses
the PXI trigger bus to interconnect timing signals between PXI devices and
the programmable function input (PFI) pin on the front SMB connector to
connect the device to external circuitry. These connections are designed to
enable the device to both control and be controlled by other devices and
circuits.
The DAQ-STC has internal timing signals you can control by an external
source. These timing signals also can be controlled by signals internally
generated to the DAQ-STC, and these selections are software configurable.
Figure 3-3 shows an example of the signal routing multiplexer controlling
the AI CONV CLK signal.
