National Instruments 653X User Manual

Page 129

Glossary

G-3

channel

Pin or wire lead to which you apply or from which you read the analog or
digital signal. For digital signals, you group channels to form ports. Ports
usually consist of either four or eight digital channels.

CompactPCI

core specification defined by the PCI Industrial Computer Manufacturer’s
Group (PICMG)

compiler

A software utility that converts a source program in a high-level
programming language, such as LabVIEW, Basic, C or Pascal, into an
object or compiled program in machine language. Compiled programs run
10 to 1,000 times faster than interpreted programs. Some languages, such
as Java, are compiled to an intermediate language that is interpreted at run
time.

control signals

Signals that regulate/control the timing of your data transfer in handshaking
I/O and pattern I/O. There are four control signals in your 653X device:
ACK (STARTTRIG), REQ, STOPTRIG, and PCLK.

counter/timer

a circuit that counts external pulses or clock pulses (timing)

CPULL

A user-configurable 2.2 k

Ω internal resistor for control lines. You can

connect the line to +5 VDC (pull up) or connect the line to ground (pull
down).

current sinking

the ability to dissipate current for analog or digital signals

current sourcing

the ability to supply current for analog or digital signals

DAQ

Data Acquisition—Collecting and measuring electrical signals from
sensors, transducers, and test probes or fixtures and inputting them to a
computer for processing. Also refers to collecting and measuring the same
kinds of electrical signals with analog-to-digital and/or digital devices
plugged into a PC, and possibly generating control signals with
digital-to-analog and/or digital devices in the same PC.

Data In Valid

data generated by peripheral device that is ready for input to the 653X
device

direct current