Chapter 3
VXI Configuration Utility
©
National Instruments Corporation
3-17
The VXI/VME-MXI-2 uses VMEbus request level 3 by default, as required
by the VXIbus specification. This is suitable for most VXIbus systems.
However, you can change the VXI/VME-MXI-2 to use any of the other
three request levels (0, 1, or 2) by changing the
Request Level
setting.
You may want to change request levels to change the priority of the
VXI/VME-MXI-2 request signal. For more information, refer to the
VMEbus specification.
VXI/VME Fair Requester
The VXI/VME-MXI-2 is always a Release On Request requester.
However, you can configure whether the VXI/VME-MXI-2 acts as
either a fair or unfair requester on the VXI/VMEbus. By default, the
VXI/VME-MXI-2 operates as a fair requester. For more information on
the different types of requesters, refer to the VMEbus specification.
MXI Bus System Controller
You can determine whether the VXI/VME-MXI-2 acts as the MXI Bus
System Controller. When the
Auto
setting (the default setting) is active,
the VXI/VME-MXI-2 automatically can sense from the MXIbus cable
whether it should be the controller.
You can select either
Yes
or
No
to manually determine if the
VXI/VME-MXI-2 should be the MXI Bus System Controller. You must
still be certain to cable the MXIbus system appropriately when you make
either of these selections.
MXI Auto Retry
The VXI/VME-MXI-2 has an automatic retry feature for cycles that map
from the MXIbus to the VXI/VMEbus. This feature works in the same
manner as the
VXI Auto Retry
feature described previously. By default,
this option is disabled.
Normally, when a cycle maps from the MXIbus to the VXI/VMEbus, the
VXI/VMEbus passes any retry response it receives to the MXIbus. If you
enable this feature, the VXI/VME-MXI-2 automatically retries any
VXI/VME cycle that receives a retry response instead of passing a retry
response on to the MXIbus. The VXI/VME-MXI-2 automatically
continues to retry the VXI/VME cycle until it receives either a
DTACK
or
BERR
response, which it then passes to the MXIbus.
