Chapter 2
Hardware Overview
©
National Instruments Corporation
2-9
Figure 2-3.
Trigger Sources
Analog Trigger Circuit
The analog trigger on the NI 5911 operates by comparing the current
analog input to an onboard threshold voltage. This threshold voltage is the
trigger value, and can be set within the current input range in 170 steps.
Therefore, for a ±10 V input range, the trigger can be set in increments of
20 V/170 = 118 mV. A hysteresis value may also be associated with the
trigger that can be set in the same size increments. The hysteresis value
creates a trigger window the signal must pass through before the trigger is
accepted. You can generate triggers on a rising or falling edge condition.
For more information on triggering, refer to Chapter 3,
Common Functions
and Examples
, of the
NI-SCOPE Software User Manual
.
a. Analog Trigger Circuit
b. Trigger and Arm Sources
Gain
Analog
Input
High
Level
Low
Level
+
–
COMP
COMP
Analog
Trigger
Circuit
ATC_OUT
Trigger
Software
ATC_OUT
RTSI<0..6>
PFI 1, PFI 2
7
2
Arm
