External Trigger Input Configuration; Figure 2-8. External Trigger Input Circuit; Figure 2-9. External Trigger Input Termination Settings - National Instruments VXIpc-486 500 Series Getting Started

Chapter 2

External Trigger Input Configuration

The external TTL trigger input interface is the SMB connector labeled TRG IN on the
VXIpc-486 front panel. Figure 2-8 shows the external trigger input circuit.
The W34 jumper configures whether the external TTL trigger input is terminated with a 50 Ω
resistor to ground. This is important only if you are daisy-chaining the external trigger input
among multiple chassis. The source of the trigger input and the last chassis in the daisy-chain
should be terminated to prevent electrical reflections. Figure 2-9 shows the external trigger input
termination settings.

Figure 2-9. External Trigger Input Termination Settings

© National Instruments Corporation
External Trigger Input Signal
TRG IN
Connector

Figure 2-8. External Trigger Input Circuit

W25
W24
W34
W33
W20 W36
W35
J16 W32
W26
a. External
Trigger Input
Unterminated*
* Factory Configuration
VXIpc-486 Configuration and Installation
W34
50Ω
W34 W34
b. External
Trigger Input
Terminated
2-9 VXIpc-486 Model 500 Series