User manual

Chapter 3 VXI-MXI-2 Configuration and Installation

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.

Use switch 2 of U35 to select whether you want the VXI-MXI-2 to

automatically control termination of the MXIbus. Switch 1 of U35 lets

you manually control whether to terminate the MXIbus when automatic

termination is turned off. Switch 1 has no effect when switch 2 is set

for automatic MXIbus termination; you must turn off automatic

termination if you want to manually control termination.