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Analog Input boards convert incoming analog signals into digital values.
The length of time the board requires to convert an analog signal into a digital value. The theoretical maximum speed (conversion/second) is the inverse of this value. See also Throughput
On-board Counter/Timer circuitry that can be set to trigger data acquisition at a user-selectable rate and for a particular length of time.
Serial communications data transmission rate expressed in bits per second (b/s)
Bipolar inputs are designed to accept voltage in the ±X Volts range, allowing positive or negative voltage inputs. Example ±5V.
One binary digit, either 0 or 1. There are eight bits to one Byte (or character); there are 1024 Bytes to one Kilobyte, and 1024 Kilobytes to one Megabyte.
Eight related bits of data, an eight-bit binary number. Also used to denote the amount of memory required to store one byte of data.
The expansion connectors built into the computer determine the bus. Boards are inserted into these connectors, and all communication between the computer and the board occurs through the computer's bus.
High-speed processor memory that buffers commonly used instructions or data to increase processing throughput.
A software program, controlled from an intuitive user interface that creates syntactically correct high-level source code in languages such as C or BASIC
Common Mode Rejection Ratio - The board's ability to measure only the difference between the leads of a transducer, rejecting Common Mode Voltage.
Thermocouple measurements can easily be affected by the interface hardware the thermocouples are connected to. Cold Junction Compensation circuitry compensates for inaccuracies introduced in the connection process.
User-accessible circuitry built into boards which can be used for event counting or frequency measurement.
This is the amount of current the board can supply for digital output signals. With 10-12 mA or more of current sink capability, you can turn relays on and off. Digital I/O boards with less and 10-12 mA of sink capability are designed for data transfer only, not hardware power relay switching.
Analog Output boards convert digital values to analog signals.
Direct Memory Access. Allows a 64KByte block of memory to be set aside for high-speed transfer of data to a PC system memory. Boards which support single DMA access can store up to 64KBytes of data (32K Samples) at speeds which can reach 250kBytes/second on XT/AT computers.
Digital Signal Processing
All of ADAC's data acquisition boards allow sampling to be triggered by a voltage pulse from an external source.
A first-in first-out memory buffer; the first data stored is the first data sent to the acceptor.
The factor by which a signal is amplified, sometimes expressed in decibels (dB)
The physical components of a computer system, such as the curcuit boards, plug-in boards, chasis, enclosures, peripherals, cables, etc.
Input/Output. The transfer of data to/from a computer system involving communications channels, operator interface devices and/or data acquisition and control interfaces.
The measured resistance and capacitance between the input terminals of a circuit.
A computer signal indicating that the CPU should suspend its current task to service a designated activity.
With the addition of multiplexing cards, up to 128 inputs can be connected to an A/D
A property of an operating system in which several processes can be run simultaneously.
An undesirable electrical signal. Noise comes from external sources such as the AC power line, motors, generators, tansformers, fluorescent lights, soldering irons, CRT displays, computers, electrical storms, welders, radio transmitters, and internal sources such as semiconductors, resistors, and capitors.
This is the number of input lines the board can sample. Single-Ended inputs share the same ground connection, while differential inputs have individual two-wire inputs for each incoming signal, allowing greater accuracy and signal isolation. See also Multiplexer.
The amount of time required for the analog output voltage to reach its final value within specified limits.
A communications connection on a computer or a remote controller
Applied to the incoming signal, gain acts as a multiplication factor on the signal, increasing the number of ranges the board is designed to accept. For example, if the ±5V range is selected and the fain is set to 10, signals in the ±0.5V (500mV) range are usable; with a gain of 20, the range would be ±250 mV.
The full-scale range the board uses is selected through the Data Acquisition software or by a hardware jumper on the board.
A property of an event or system in which data is processed as it is acquired instead of being accumulated and processed at a later time.
The resolution is the number of bits in which a digitized value will be stored. This represents the number of division into which the full scale range will be divided. e.g. A 0-10V range with a 12 bit resolution will have 4096 (212) divisions of 2.44mV each (10V/212) or 10V/4096.
Resistance Temperature Detector; a metallic probe that measures temperature based upon its coefficient of resistivity.
A device that responds to a physical stimulus (heat, light, sound, pressure, motion, flow, etc.) and produces a corresponding electrial signal.
The ratio of the overall rms signal level to the rms noise level, expressed in dB.
Typically a set of programs or subroutines allowing the user to control basic board functions, such as setup and data acquisition. These can be incorporated into user-written programs to create a simple but functional data acquisition system.
Indicates that the board allows software control of data acquisition triggering.
A sensor whose resistance is a function of the applied force.
The throughput rate of an A/D system is defined as the reciprocal time taken, once triggered, for the multiplexer and sample and hold to settle and for the converter to complete its conversion process. It does not include software instruction time to retrieve the data and store it in memory.
Any device which generates an electrical signal from real-world measurements, e.g. strain gauges, thermocouples, RTD's etc. See also Sensor
When set to accept a unipolar signal, the channel detects and converts only positive voltages in the 0-X Volts Range. (Example: 0-10V).