Measurement Computing Data Acquisition Systems rev.10.4 - Manual (Page 365)

Programmer’s Manual
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Glossary G-7
Software Trigger
A trigger event that is detected in the DaqX driver-software. These types of triggers normally result in higher
trigger detection latencies but are much more flexible than hardware trigger events.
Stop Event
An event that terminates the acquisition of post-trigger data. This event, when satisfied, will cause the device to
stop collecting post-trigger data.
T/C (Thermocouple)
A thermocouple is a transducer that produces a voltage relative to temperature at the junction of two dissimilar
metals. Various types of thermocouples are available, each having characteristics particular to certain temperature
ranges. For programming, this term generally refers to a channel that has a thermocouple connected to it.
T/C (Thermocouple) Channel
A thermocouple channel on a temperature measurement module or temperature expansion card.
Transistor-Transistor Logic (TTL)
Transistor-Transistor Logic (TTL) is a circuit in which a multiple-emitter transistor has replaced the multiple diode
cluster (of the diode-transistor logic circuit); typically used to communicate logic signals at 5 V.
Trigger/Start Event
An event that initiates the acquisition of post-trigger data. This event, when satisfied, will cause the device to begin
to collect post-trigger data.
Unipolar
A range of analog signals that is always zero or positive (e.g., 0 to 10 V). Evaluating a signal in the right range
(unipolar or bipolar) allows greater resolution by using the full-range of the corresponding digital value. Also see
bipolar.
Update Block
The data for all output channels that are part of a waveform/pattern output operation.
Update Clock
A pulse from an internal or external source that causes all waveform/pattern output channels to be updated
synchronously.
Update Rate/Frequency
The rate at which update blocks should be presented to the outputs when using an internal clock source for the
waveform/pattern output operation.
Update Sample
The data for just one output channel that is part of a waveform/pattern output operation.
Waveform/pattern output
A clocked, synchronous output operation [from PC memory or disk file] to one or more valid DAC or Digital
Output channels. D/A and digital output data are output synchronously from the device’s built-in output FIFO,
which is fed from PC memory or disk file. Output updates are presented synchronously to each of the output ports
based upon an external or internal clock pulse.
WORD
A 16-bit unsigned integer (2 bytes) quantity that can range from 0 to 65,535. This parameter type should be passed
by value according to the dictates of the programming language used.