58
Operation Theory
level for SRC1 is ±10V and the resolution is 78mV (please refer to
Table 4-6), while the trigger range of SRC2 is the full-scale range
of the selected channel input, and the resolution is the desired
range divided by 256. For example, if the channel input selected to
be the trigger source is set bipolar and ±5V range, the trigger volt-
age would be 4.96V when the trigger level code is set to 0xFF
while 0V when the code is set to 0x80.
Figure 4-31: Analog trigger block diagram
The trigger signal is generated when the analog trigger condition
is satis-fied. There are five analog trigger conditions in the DAQ/
PXI-20XX. The DAQ/PXI-20XX uses 2 threshold voltages,
Low_Threshold and High_Threshold to build the 5 different trigger
conditions. Users could configure the trigger conditions easily by
software.
Trigger Level digital setting Trigger voltage
0xFF
9.92V
0xFE
9.84V
---
---
0x81
0.08V
0x80
0
0x7F
-0.08V
---
---
0x01
-9.92V
Table 4-7: Analog trigger SRC1 (EXTATRIG) ideal transfer characteristic
Summary of Contents for DAQ/PXI-20 Series
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