Operation Theory
45
value. Figure 4-24 illustrates the generation of two pulses with
pulse delay of four and pulse-width of three.
Figure 4-24: Mode 8 Operation
4.5 Trigger Sources
We provide flexible trigger selections in DAQ/PXI-2500 SERIES.
In addi-tion to software trigger, DAQ/PXI-2500 SERIES also sup-
ports external analog and digital triggers. Users can configure the
trigger source for A/D and D/A processes individually via software.
NOTE
: A/D and D/A conversion share the same analog trigger.
Software-Trigger
This trigger mode does not need any external trigger source. The
trigger asserts right after users execute the specified function call.
A/D and D/A processes can receive an individual software trigger.
External Analog Trigger
The analog trigger circuitry routing is shown in the Figure 4.5.1.
The analog multiplexer selects either a direct analog input from
the EXTATRIG pin (SRC1 in Figure 4-25) on the 68-pin connector
CN1 or the input signal of ADC (SRC2 in Figure 4-25). The range
of trigger level for SRC1 is ±10V and the resolution is 78mV
(please refer to Table4-8), while the trigger range of SRC2 is the
full-scale range of AD input, and the resolution is the desired
range divided by 256.