User manual

Chapter 4 VXI-MXI-2/B Configuration and Installation
VXI-MXI-2 User Manual 4-12 © National Instruments Corporation
Trigger Input Termination
You can use switch S5 to terminate the external trigger input SMB with
50 Ω. Figure 4-8a shows the default setting for a nonterminated trigger
input SMB. Use the setting of Figure 4-8b to terminate the trigger input
SMB.
a. Non-Terminated External Trigger
Input SMB (Default)
b. Terminated External Trigger
Input SMB with 50 Ω
( = NO)
TERM TRIGIN
S5
( = NO)
TERM TRIGIN
S5
Figure 4-8. SMB Trigger Input Termination
MXIbus Termination
The first and last MXIbus devices connected to the MXIbus—whether
it is a single MXI-2 cable or daisy-chained MXI-2 cables—must
terminate the MXIbus. Any MXIbus devices in the middle of a MXIbus
daisy chain must not terminate the MXIbus.
The VXI-MXI-2/B automatically senses whether it is at either end of
the MXIbus cable to terminate the MXIbus. You can manually control
MXIbus termination by defeating the automatic circuitry. Use switches
3 and 4 of the four-position switch at location U21 to control whether
MXIbus termination is automatic (Figure 4-9a), on (Figure 4-9b), or off
(Figure 4-9c). The settings of switches 1 and 2 have no effect on
MXIbus termination.
Use switch 3 to select whether you want the VXI-MXI-2/B to
automatically control termination of the MXIbus. Switch 4 lets you
manually control whether to terminate the MXIbus when automatic
termination is turned off. Switch 4 has no effect when switch 3 is set
for automatic MXIbus termination; you must turn off automatic
termination if you want to manually control termination.