Glossary
© National Instruments Corporation
Glossary-3
VXI-AT2000/NI-VXI MS-DOS Getting Started
D
DACK
DMA Acknowledge
daisy-chain
A method of propagating signals along a bus, in which the devices are
prioritized on the basis of their position on the bus.
Data Transfer Bus
DTB; one of four buses on the VMEbus backplane. The DTB is used by a
bus master to transfer binary data between itself and a slave device.
DIP
Dual Inline Package
DMA
Direct Memory Access; a method by which data is transferred between
devices and internal memory without intervention of the central
processing unit.
DRQ
DMA Request
DTB
See Data Transfer Bus.
dynamic
A method of automatically assigning logical addresses to VXIbus devices
configuration
at system startup or other configuration times.
dynamically
A device that has its logical address assigned by the Resource Manager.
configured device
A VXI device initially responds at Logical Address 255 when its MODID
line is asserted. A MXIbus device responds at Logical Address 255
during a priority select cycle. The Resource Manager subsequently
assigns it a new logical address, which the device responds to until
powered down.
E
ECL
Emitter-Coupled Logic
embedded
An intelligent CPU (controller) interface plugged directly into the VXI
controller
backplane, giving it direct access to the VXIbus. It must have all of its
required VXI interface capabilities built in.
EMI
Electromagnetic Interference
external controller
In this configuration, a plug-in interface board in a computer is connected
to the VXI mainframe via one or more VXIbus extended controllers. The
computer then exerts overall control over VXIbus system operations.
F
F
Fahrenheit
fair requester
A MXIbus master that will not arbitrate for the MXIbus after releasing it
until it detects the bus request signal inactive. This ensures that all
requesting devices will be granted use of the bus.
