Chapter 4 VME-MXI-2 Configuration and Installation
©
National Instruments Corporation 4-3 VXI/VME-PCI802 2 for Sola ris
Front Panel Features
The VME-MXI-2 has the following front panel features.
• Three front panel LEDs
–SYSFAIL LED indicates that the VMEbus SYSFAIL line is
asserted.
–MXI LED indicates when the VME-MXI-2 is accessed from
the MXIbus.
–VME LED indicates when the VME-MXI-2 is accessed from
the VMEbus.
• MXIbus connector
• System reset push-button
VMEbus A16 Base Address
The VME-MXI-2 requires 64 bytes of A16 space for its configuration
registers. It uses the logical address scheme of the VXIbus
specification, in which each device is assigned an 8-bit value called the
logical address. This logical address allocates 64 bytes of space to the
device within the upper quarter of A16 space. The VME-MXI-2 cannot
be configured to locate its registers in the lower three quarters of A16
space. The A16 base address of the VME-MXI-2 will be address
lines 15 a nd 14 high with address lines 13 through 6 ma tching the
logical address of the VME-MXI-2, and address lines 5 through 0 low.
In other words, the A16 base address of the VME-MXI-2 module’s
64-byte register set is as calculated below:
base address = C000 hex + (logical address) * 40 hex
The factory-default logical address for the VME-MXI-2 is 1, which
locates the registers in the range C040 hex to C07F hex. You can change
the logical address of the VME-MXI-2 by changing the setting of the
8-bit DIP switch at location designator U20. The ON position of the DIP
switch corresponds to a logic value of 0, and the OFF position
corresponds to a logic value of 1. Allowable logical addresses for the
VME-MXI-2 range from 1 to 254 (hex FE). Verify that no other devices
in your system use the A16 address space for the VME-MXI-2. I f
possible, configure all other VMEbus A16 devices to be located within
the lower three quarters of A16 space. Also, when setting base
addresses, keep in mind the grouping requirements set by the system
hierarchy. See VXI-6, VXIbus Mainframe Extender Specification, for