VXi 320222-01 User Manual

Page of 209
Configuration and Installation
Chapter 3
VXI-MXI User Manual
3-8
© National Instruments Corporation
a.  Level 3 Requester (default)
VMEbus Request Level
b.  Level 2 Requester 
VMEbus Request Level
c.  Level 1 Requester
VMEbus Request Level
d.  Level 0 Requester
VMEbus Request Level
Figure 3-6.  VMEbus Requester Jumper Settings
VMEbus Timeout Value
When a VXI-MXI is installed in a VXIbus mainframe, the VME Bus Timeout Unit (BTO)
circuitry for the VXIbus mainframe must be on the VXI-MXI.  If there are multiple VXI-MXI
interfaces in a mainframe, the BTO must be enabled on one of them and they must be in adjacent
slots.  In the case of multiple VXI-MXIs, it is recommended that the BTO be enabled on the
VXI-MXI that is installed in Slot 0.  The BTO monitors the current bus cycle and asserts the bus
error (BERR) signal if a data transfer acknowledge (DTACK) or BERR is not received from the
selected slave within the given amount of time after data strobe (DS1 or DS0) becomes active.
Whenever a MXIbus transfer into or out of the VXI-MXI occurs, the VMEbus timeout on the
VXI-MXI is disabled and the MXIbus System Controller BTO monitors the transfer.  This