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Embedded Single-Slot VXIbus Controllers

VXIbus

VXI Addressing – The VXIpc-77x controllers feature the MITE and

MANTIS custom ASICs for access to the VXI backplane resources. To

access VXI memory or VXI devices, the controllers use the multiple

windowing scheme of the MITE, so you can access all of the VXI

address space. The MITE exports independent VXI address windows,

providing the user with three completely user-configurable windows.

You can use one or all three windows; you can also set each window

size and location. This multiple windowing scheme alleviates the

performance penalty related to the context switching of one window

that you must constantly move between the different address spaces.

DMA Transfers to and from VXI – A VXIpc-77x controller can perform

block-mode transfers using one of the two on-chip DMA controllers

on the MITE. Controlling external VXI devices often takes valuable

CPU time because the microprocessor typically shoulders the burden

of transferring data to and from devices. MITE-based VXI controllers,

such as those of the VXIpc-77x, move the burden of block data

transfers to one of the DMA controllers integrated in the MITE and

free CPU processing time. Instead of the computer microprocessor

transferring the data and/or commands, the NI-VXI/NI-VISA

software executes the block data transfers with the MITE ASIC. While

the MITE transfers the data, the processor can perform application-

specific tasks, such as data presentation and analysis.

VXI Slot 0 Functionality – VXIpc-77x controllers have full VXI Slot 0

capability, including a MODID register and a CLK10 source, as

required by the VXIbus specification. You can also install a

VXIpc-77x controller in another slot and use it in the non-Slot 0

mode. No matter what your configuration needs, VXIpc-77x

controllers can automatically detect whether they are inserted into

Slot 0 and automatically enable or disable the Slot 0 onboard

circuitry without switches and jumpers.

External VXI CLK10 Synchronization – VXIpc-77x controllers have

SMB connectors on the front panel for an external clock. Onboard

programmable logic can configure the controller and its 10 MHz VXI

CLK10 signal to this connector as an output, or use this connector as

an input for the 10 MHz VXI CLK10 signal. With a VXIpc-77x

controller, you can configure multiple mainframes to operate off a

single 10 MHz system clock.

Advanced Trigger/Timing – With a VXIpc-77x controller, you have full

software and hardware control of the VXI trigger lines. The VXIpc-77x

controllers have two SMB trigger I/O connectors on their front panel

for routing any TTL trigger line between the backplane and external

devices. VXIpc-77 controllers can respond to all VXI-defined protocols

on all P2 TTL and ECL trigger lines simultaneously. The hardware also

includes an internal counter, which gives sophisticated counting of

events and interrupting on trigger edges and pulses, as well as

generating pulse trains, variable length pulses, and pulse stretching.

VXI Interrupts – A VXIpc-77x controller can function as an

interrupter and an interrupt handler for any or all of the VXIbus

interrupt lines in a VXI mainframe. The NI-VXI/NI-VISA software

can notify your application when any interrupt is asserted, and can

assert any interrupt level with a programmable status. You can assign

which interrupt levels should be handled by each device in the system

with the NI-VXI configuration software.

Software

VXIpc-77x controllers include NI-VXI/NI-VISA software, making

them completely compliant with VXIplug&play Systems Alliance

specifications. NI-VXI/NI-VISA is the combination of our popular

NI-VXI VXI bus interface software and our new-generation virtual

instrumentation software architecture VISA I/O software, also

standardized by the VXIplug&play Systems Alliance. Because

VXIpc-77x controllers are completely VXIplug&play-compliant, you can

run all the latest VXIplug&play software, including executable soft front

panels. With these panels, you can operate the instrument immediately,

and standardized LabVIEW, LabWindows/CVI, and Measurement

Studio instrument drivers simplify your programming task.

NI-VXI/NI-VISA comes with a VXI bus interface library that you

can use with a number of popular programming environments

and compilers, including LabVIEW, LabWindows/CVI, Measurement

Studio, Microsoft Visual C++, Borland C++, and Microsoft Visual

Basic. NI also offers industry-standard NI-488.2 software for

controlling external GPIB instruments through the front-panel GPIB

port. Application software developed using the VXIpc-77x controllers

and the NI-VXI/NI-VISA bus interface software is compatible with

many other VXI controller platforms, including computers equipped

with a MXI-2- or MXI-3-based interface. NI-VXI and NI-VISA I/O

software compatibility across platforms protects your software

investment in the future. Because the software for all these

configurations is compatible, you can program both general-purpose

external PCs and embedded VXIpc controllers using the same

programming tools and concepts. You can easily port VXI software to

other platforms as your controller requirements change or expand in

the future. The NI-VXI and NI-DAQ software for the VXIpc-77x

controllers is not compatible with National Instruments legacy VXI

data acquisition and signal conditioning devices. Please see technical