Chapter 3
VXI-MXI-2 Configuration and Installation
©
National Instruments Corporation
3-13
Figure 3-8.
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 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 1 and 2
of the four-position switch at location U35 to control whether MXIbus
termination is automatic (Figure 3-9a), on (Figure 3-9b), or off
(Figure 3-9c). The settings of switches 3 and 4 have no effect on MXIbus
termination.
a. Non-Terminated External Trigger Input SMB (Default)
S2 Off
On
50
W
Termination for External Trigger Input
S3 Out
In
S4 Off
On
NON-INVERTED
INVERTED
S5
SMB CLK10 Direction
50
W
Termination for SMB CLK10 (Effective only when S3 is set to “IN”
SMB CLK10 Output Polarity (Effective only when S3 is set to “OUT”)
S2 Off
On
50
W
Termination for External Trigger Input
S3 Out
In
S4 Off
On
NON-INVERTED
INVERTED
S5
SMB CLK10 Direction
50
W
Termination for SMB CLK10 (Effective only when S3 is set to “IN”)
SMB CLK10 Output Polarity (Effective only when S3 is set to “OUT”)
b. Terminated External Trigger Input SMB with 50
