National Instruments USB-621 Series User Manual page 192

trigger
t
sc
t
sp
TTL
U
USB
V
V
V
cm
V
g
V
IH
V
IL
V
in
V
m
V
OH
V
OL
V
out
© National Instruments Corporation
1. Any event that causes or starts some form of data capture.
2. An external stimulus that initiates one or more instrument functions.
Trigger stimuli include a front panel button, an external input voltage
pulse, or a bus trigger command. The trigger may also be derived from
attributes of the actual signal to be acquired, such as the level and slope
of the signal.
Source clock period.
Source pulse width.
Transistor-Transistor Logic—A digital circuit composed of bipolar
transistors wired in a certain manner. A typical medium-speed digital
technology. Nominal TTL logic levels are 0 and 5 V.
Universal Serial Bus—A 480 Mbit/s serial bus with up to 12-Mbps
bandwidth for connecting computers to keyboards, printers, and other
peripheral devices. USB 2.0 retains compatibility with the original USB
specification.
Volts.
Common-mode voltage.
Ground loop voltage.
Volts, input high.
Volts, input low.
Volts in.
Measured voltage.
Volts, output high.
Volts, output low.
Volts out.
G-15
Glossary
NI USB-621x User Manual