Chapter 3
Hardware Overview
©
National Instruments Corporation
3-13
PCI-MIO E Series User Manual
Analog Trigger
♦
PCI-MIO-16E-1, PCI-MIO-16E-4, and PCI-MIO-16XE-10
In addition to supporting internal software triggering and external
digital triggering to initiate a data acquisition sequence, the
PCI-MIO-16E-1, PCI-MIO-16E-4, and PCI-MIO-16XE-10 also
support analog triggering. You can configure the analog trigger
circuitry to accept either a direct analog input from the PFI0/TRIG1 pin
on the I/O connector or a postgain signal from the output of the PGIA,
as shown in Figure 3-5. The trigger-level range for the direct analog
channel is
±
10 V in 78 mV steps for the PCI-MIO-16E-1 and
PCI-MIO-16E-4, and
±
10 V in 4.9 mV steps for the
PCI-MIO-16XE-10. The range for the post-PGIA trigger selection is
simply the full-scale range of the selected channel, and the resolution is
that range divided by 256 for the PCI-MIO-16E-1 and PCI-MIO-16E-4,
and divided by 4,096 for the PCI-MIO-16XE-10.
Note:
The PFI0/TRIG1 pin is an analog input when configured as an analog
trigger. Therefore, it is susceptible to crosstalk from adjacent pins, which
can result in false triggering when the pin is left unconnected. To avoid
false triggering, make sure this pin is connected to a low-impedance signal
source (less than 1 k
Ω
source impedance) if you plan to enable this input
via software.
Figure 3-5. Analog Trigger Block Diagram
Analog
Input
Channels
PFI0/TRIG1
PGIA
+
-
ADC
DAQ-STC
Analog
Trigger
Circuit
Mux