Chapter 1
Introduction
© National Instruments Corporation
1-3
VME-MXI-2 User Manual
VMEbus address spaces (A32, A24, and A16) plus a dedicated window
for mapping the VXIbus configuration space (the upper 16 KB of A16
space).
The MXIbus is a multidrop system bus that connects multiple devices
at the hardware bus level in a software-transparent manner. Multiple
VMEbus mainframes with VME-MXI-2 interfaces can be connected to
form a single multiframe VMEbus system. An external PC with a
MXIbus interface can also be connected to a VMEbus mainframe with
a VME-MXI-2. This configuration makes the PC function as though it
were an embedded VMEbus controller that is plugged into the VMEbus
mainframe.
Multiple MXIbus devices are tightly coupled by mapping together
portions of each device’s address space and locking the internal
hardware bus cycles to the MXIbus. The window address circuitry on
each MXIbus device monitors internal local bus cycles to detect bus
cycles that map across the MXIbus. Similarly, external MXIbus cycles
are monitored to detect MXIbus cycles that map into the VMEbus
system. MXIbus devices can operate in parallel at full speed over their
local system bus and need to synchronize operation with another device
only when addressing or being addressed by a resource located on
another MXIbus device. The MXIbus device originating the transaction
must gain ownership of both the MXIbus and the local bus in the target
MXIbus device. All hardware bus cycles are then coupled across the
MXIbus and local buses before the transfer completes.
The VME-MXI-2 has the following features:
•
Interfaces the VMEbus to the MXIbus (32-bit Multisystem
eXtension Interface bus)
•
Extends VMEbus to multiple mainframes, external MXIbus-
equipped instruments, and external MXIbus-equipped PCs
•
Allows multiple VMEbus mainframes to operate as a single
VMEbus system
•
Supports the VME RETRY* signal to resolve deadlock conditions
•
Supports D64, block, and synchronous MXI cycles for high-
performance data transfers
•
Two independent DMA controllers for data transfer
•
Can extend VMEbus interrupt levels and utility signals to the
MXIbus
•
Can operate in either one of two modes: parallel or interlocked
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
