Chapter 3 VXI-MXI-2 Configuration and Installation
©
National Instruments Corporation 3-13 VXI/VME-PCI802 2 for Sola ris
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 (Figure3-9a), 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 Ω Termination for External Trigger Input
S3 Out In
S4 Off On
NON-INVERTED
INVERTED
S5
SMB CLK10 Direction
50 Ω 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 Ω

S2 Off On 50 Ω Termination for External Trigger Input
S3 Out In
S4 Off On
NON-INVERTED
INVERTED
S5
SMB CLK10 Direction
50 Ω Termination for SMB CLK10 (Effective only when S3 is set to "IN")
SMB CLK10 Output Polarity (Effective only when S3 is set to "OUT")