Measurement Computing Data Acquisition Systems rev.10.4 - Manual (Page 362)

G-4 Glossary
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Programmer’s Manual
Disarm
An action that disables the ability of the device to detect the trigger/start event specified. If the trigger/event has
already occurred, the disarm action will stop the current operation.
DOUBLE
A 64-bit double precision (8 bytes) floating point number. This parameter type should be passed by value according
to the dictates of the programming language used.
DWORD
A 32-bit unsigned integer (4 bytes) quantity that can range from 0 to 4,294,967,295. This parameter type should be
passed by value according to the dictates of the programming language used.
External clock
The external clock is a device that uses pulses to drive synchronized input or output operations. The pulses originate
in a foreign device, such as a machine, to which the external clock is connected.
Falling/Negative edge
Describes an event in which an input signal has exceeded or reached a particular level with a negative slope. This
normally refers to a trigger or start event, or the manner in which a counter detects an event that should be counted.
False
The “false” value of a Boolean data type (= 0). Also See True and Boolean.
Flag
See Bit Mask.
FIFO (First In, First Out)
A mechanism for buffering input or output data on the device. This mechanism alleviates possible loss of data when
transmitting clocked or synchronous data due to inherent system latencies in either the PC or controlling application.
FLOAT
A 32-bit single precision (4 bytes) floating point number. This parameter type should be passed by value according
to the dictates of the programming language used.
Frequency Output (fout)
The output frequency programmed for a particular timer output channel. The frequency represents the rate at which
the timer generates an output pulse.
Function
Normally, this refers to a DaqX API command. The command or function is accessible through the DaqX API
support files.
Gain
The degree to which an input signal is amplified (or attenuated) to allow greater accuracy and resolution; can be
expressed as × n (where n is some integer), or ±dB. In terms of programming, most device channels can have their
gain value programmed. Gain codes are provided in the API for each device gain applicable.
Handle
An integer that represents the device when the device is being accessed, after the device session has been opened.
The handle to the device may be obtained via the daqOpen command.
Hardware Trigger
A trigger event that is detected on the device. Usually, these triggers take the form of an analog level or TTL level
signal. These types of triggers normally result in lower trigger detection latencies, but are not as flexible as software
trigger events.