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Chapter 2
Hardware Configuration and Installation
VME Address
The SB-MXI and the VME-MXI use VME short (A16) address space for their configuration,
communication, and status registers. Because both boards are not only VMEbus-compatible but
are also compatible with the VXIbus specification, each board has an associated logical address.
The logical address assigns a unique 64-byte block of address space in the upper 16 KB of A16
space to each board. You can use the following formula to calculate the starting address of a
device's address space:
starting address (A16 space) = (logical address * 40h) + C000h
The SB-MXI is responsible for configuring the system upon power-up or reset and is referred to
as the System Resource Manager. Because the System Resource Manager is defined to have a
logical address of 0, the SB-MXI will use A16 address space from C000h through C03Fh. The
logical address of the SB-MXI is software configurable, but you should not change this setting
when using the SB-MXI with a VME system.
The VME-MXI is factory configured with a logical address of 1, meaning that it occupies
A16 space in the range of C040h through C07Fh. The logical address of the VME-MXI is
configurable via an onboard switch, but you should not change this setting unless you are using
multiple VME-MXIs in your system. If this is the case, refer to the VME-MXI User Manual
that came with your additional VME-MXIs for more information.
Ensure that no other VMEbus devices in your system occupy address space used by the SB-MXI
or the VME-MXI. If they do, change the other VME devices so that they occupy unique
portions of address space. It is recommended that any A16 devices have their operational
registers in the lower three-quarters of A16 space (below C000h), leaving the upper quarter for
logical addresses. This is required if the VME-MXI is part of a VXIbus system. In addition, if
you are installing the VME-MXI in a VXIbus system, make sure that no other VXIbus devices
are statically configured at either Logical Address 0 or 1.
VMEbus Request Level Selection
The VME-MXI uses one of the four VMEbus request levels to request use of the VME Data
Transfer Bus (DTB). The VME-MXI requests use of the DTB whenever an external MXIbus
device, such as a Sun workstation with an SB-MXI interface, attempts a transfer that maps into
the VMEbus chassis.
The VME-MXI is factory configured to use VMEbus request level 3. This is the highest
priority request level and is suitable for most VMEbus systems. However, you can change
the VME-MXI to use any of the other three request levels (0, 1, or 2) by changing the jumper
configuration of the three pin arrays at locations W2, W3, W4, W5, and W6. You may want
to change request levels to change the priority of the VME-MXI request signal. For more
information, refer to the VMEbus specification.
© National Instruments Corporation
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VME-SB2020/NI-VXI/Solaris Getting Started
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