Front Panel Features; Vmebus A16 Base Address - National Instruments MXI-2 Reference Manual

Front Panel Features

VMEbus A16 Base Address

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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 pushbutton
The VME-MXI-2 requires 64 B (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 B 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 is address lines 15 and 14 high with address lines 13
through 6 matching 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 B 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. If 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. Refer to VXI-6, VXIbus Mainframe Extender Specification, for
more information on setting base addresses on a multichassis hierarchy.
Chapter 7 VME-MXI-2 Configuration and Installation
7-3 MXI-2 Configuration Reference Manual