National Instruments NI-VXI - Manual (Page 126)

Glossary
© National Instruments Corporation G-3 NI-VXI User Manual
BAV Word Serial Byte Available command. Used to transfer 8 bits of data
from a Commander to its Servant under the Word Serial Protocol.
BERR* Bus error signal. This signal is asserted by either a slave device or the
bus time out (BTO) unit when an incorrect transfer is made on the Data
Transfer Bus (DTB). The BERR* signal is also used in VXI for certain
protocol implementations such as writes to a full Signal register and
synchronization under the Fast Handshake Word Serial Protocol.
binary A numbering system with a base of 2.
bit Binary digit. The smallest possible unit of data: a two-state, yes/no,
0/1 alternative. The building block of binary coding and numbering
systems. Several bits make up a byte.
bit vector A string of related bits in which each bit has a specific meaning.
BREQ Word Serial Byte Request query. Used to transfer 8 bits of data from a
Servant to its Commander under the Word Serial Protocol.
BTO See bus timeout unit.
buffer Temporary memory/storage location for holding data before it can be
transmitted elsewhere.
bus master A device that is capable of requesting the Data Transfer Bus (DTB) for
the purpose of accessing a slave device.
bus timeout unit A VMEbus functional module that times the duration of each data
transfer on the Data Transfer Bus (DTB) and terminates the DTB cycle
if the duration is excessive. Without the termination capability of this
module, a bus master could attempt to access a nonexistent slave,
resulting in an indefinitely long wait for a slave response.
byte A grouping of adjacent binary digits operated on by the computer as a
single unit. A byte consists of 8 bits.
byte order How bytes are arranged within a word or how words are arranged
within a longword. Motorola ordering stores the most significant byte
(MSB) or word first, followed by the least significant byte (LSB) or
word. Intel ordering stores the LSB or word first, followed by the
MSB or word.