National Instruments 653X Manuale Utente
Glossary
© National Instruments Corporation
G-5
G
group
A collection of one, two, or four ports and an associated timing controller.
All buffered operations must be performed on groups.
All buffered operations must be performed on groups.
H
handshaking I/O
Data-transfer mode in which the 653X device engages in a two-way
communication with the peripheral device. The 653X asserts a signal, ACK,
when it is ready for a data transfer and the peripheral device asserts a
separate signal, REQ, when it is ready for a data transfer. Data is transferred
only when both the 653X and the peripheral device are ready.
communication with the peripheral device. The 653X asserts a signal, ACK,
when it is ready for a data transfer and the peripheral device asserts a
separate signal, REQ, when it is ready for a data transfer. Data is transferred
only when both the 653X and the peripheral device are ready.
I
interrupt
a computer signal indicating that the CPU should suspend its current task
to service a designated activity
to service a designated activity
I/O
Input/Output—a transfer of data to/from a computer system involving
communications channels, operator interface devices, and/or data
acquisition and control interfaces
communications channels, operator interface devices, and/or data
acquisition and control interfaces
K
k
Kilo—the standard metric prefix for 1,000, or 10
3
, used with units of
measure such as volts, hertz, and meters
L
line
Individual digital bit
LSB
Least significant bit
low/high
Refers to the active, or “on” state of handshaking I/O lines. For example, if
ACK is active low, the 653X device is ready when its ACK line asserts
(changes to) low.
ACK is active low, the 653X device is ready when its ACK line asserts
(changes to) low.