ActiveX Microsoft's toolkit for Web developers, using OLE and incorporating Sun's Java language. ActiveX helps in building software to integrate with Microsoft's Internet Explorer, or any ActiveX container such as programs written with Microsoft's Visual Studio.
Actuator In a closed-loop control system, that part of the final control element that translates the control signal into action by the control device.
AS-I (Actuator-Sensor Interface) A low-cost electromechanical connection system designed to operate over a two-2ire cable carrying data and power over a distance of up to 100m, or more if repeaters are used. Visit www.as-interface.com for more information.
Analog Input Module This is a odule that contains circuits that convert analog dc input signals to digital values that can be manipulated by the processor. By implication, these analog inputs are usually direct (i.e., a data table value directly reflects the analog signal value).
B
Bar Code A series of horizontal stripes or bars of varying width which represent a string of characters that can be read by a bar code reader (scanner) .
Bill of Materials (BOM) A list of components, ingredients, or materials needed to manufacture a product; the hierarchy of materials or components making up a product or subassembly including the proper ratios of quantities of each item.
Brushless Servomotor A class of servomotors which operates using electronic commutation of phase currents rather than electromechanical (brushes) commutation. Commutation is a function of rotor position. These motors typically have a permanent magnet rotor and wound stator.
C
CAD (Computer Aided Design) Programs used to design architectural, mechanical and electrical engineering drawings.
CAM (Computer Aided Manufacturing) Programs used to control manufacturing equipment.
Computer Integrated Manufacturing (CIM) A term used for describing a high level of automation in a manufacturing enterprise.
CMOS (Complimentary Metal-Oxide-Semiconductor) Family of logic devices that uses p-type and n-type channel devices on the same IC. It has the advantage of offering medium speed and very low power requirements.
ControlNet A real-time, control-layer network providing high-speed transport of both time-critical IO data and messaging data, including upload/download of programming and configuration data and peer-to-peer messaging, on a single physical media link. Conveyor A horizontal, inclined or vertical device for moving or transporting bulk materials, packages, or objects in a path predetermined by the design of the device and having points of loading and discharge fixed, or selective.
Crossdocking In warehouse management, sending parts from receiving directly to shipping to be placed in outgoing orders. Crossdocking allows orders to be filled quickly and precludes parts from staying in a warehouse long enough to be counted as inventory.
D
DAC (Digital-to-Analog Converter) An electronic device, often an integrated circuit, that converts a digital number into a corresponding analog voltage or current
Data Acquisition A term commonly used for equipment or software that gathers data from devices through a communications channel.
p
PAS Process Automation system
PRT Platinum resistance thermometers
Pamux A high-speed, high-density distributed I/O system that accommodates both digital and analog I/O modules. Pamux supports up to 32 stations containing up to 512 I/O points. Contact OPTO22 for more information.
PCI (Peripheral Component Interconnect) A high-performance expansion bus architecture originally developed by Intel to replace ISA and EISA. It is achieving widespread acceptance as a standard for PCs and workstations; it offers a theoretical maximum transfer rate of 132 Mbytes/s.
Prgrammable Controller An electornic device that can be programmed to control a process or machine operation using input and output signals etc .
PCM (Pulse Coded Modulation) A method of encoding information in a signal by varying the amplitude of pulses. The most common method of encoding an analog signal into a digital bit stream, usually 16 bits per sample.
PID Loop An I/O element used to drive an analog input toward a particular value (called the setpoint) and to keep the input very close to that value. PID loops include a gain term (abbreviated P for proportional, which is the inverse of gain), an integral term (I), and a derivative term (D). Temperature control is a typical application for a PID.
PLC (Programmable Logic Controller) A class of industrially hardened devices that provides hardware interface for input sensors and output actuators. PLCs can be programmed using relay ladder logic to control the outputs based on input conditions and / or algorithms contained in the memory of the PLC.
Priority Inversion An unwanted software situation in which a high-priority task is delayed while waiting for access to a shared resource that is not even being used at the time. For all practical purposes, the priority of this task has been lowered during the delay period.
Profibus Vendor-independent open fieldbus standard for use in manufacturing and building automation as well as process control. Utilizes a non-powered two-wire (RS485) network. PROFIBUS is standardized under the European Fieldbus Standard EN 50 170. Includes 3 versions - FMS, DP and PA. Visit www.profibus.com for more information.
PROM (Programmable Read-Only Memory) A type of ROM that can be written (programmed) with a device programmer. These memory devices can be programmed only once, so they are sometimes referred to as write-once or one-time programmable devices.
PWM (Pulse Width Modulation) A switch-mode control method used in amplifiers and drivers to control motor voltage and current to obtain higher efficiency than linear control. PWM refers to variable on/off times (or width) of the voltage pulses applied to the transistors.
Q
Quadrature A technique that separates signal channels by 90ø (electrical) in feedback devices. It is used with encoders and resolvers to detect direction of motion.
R
Redundancy The capacity to switch from primary equipment to standby equipment automatically without affecting the process under control.
Relay Ladder Logic This programming language expresses a program as a series of "coils" and "contacts", simulating the operation of electromechanical relays. The resultant program is the equivalent of a boolean equation, which is executed continuously in a combinatorial manner. The advantage of this language is the familiarity many electricians have with the simple operation of relays. Disadvantages include the complexity of large, cross-connected programs, and the difficulty of expressing such non-binary functions as motion control and analog I/O.
Remote Access Access to a network in another location.
Ribbon Cable A flat cable in which the conductors are arranged side-by-side. Also called flat-ribbon cable.
RS232 A standard for serial transmission of data between two devices. This defines the pin and plug in terms of size, shape and number of pins. An interface based on the RS232 standard.
RS422 A standard for serial transmission of data between two devices. This defines the pin and plug in terms of size, shape and number of pins. An interface based on the RS422 standard. Allows longer distances between devices than RS232.
RS485 A standard for serial transmission of data between multiple devices. This defines the pin and plug in terms of size, shape and number of pins. An interface based on the RS485 standard.
RTOS (Real-Time Operating System) An operating system designed specifically for use in real-time systems that respond to external events within a short and predictable time frame.
RTX Real time extension for Windows NT developed by
S
Sampling Rate The frequency with which samples of a physical variable, such as sound are taken. The higher the sampling rate, the more closely the digitized result resembles the original.
Scan Time The time to completely execute a PLC program once, including I/O update.
SCADA (Supervisory Control and Data Acquisition) The level of applications that monitor and control devices such as programmable controllers. These systems are usually PC or workstation based.
SDS (Smart Distributed System) An advanced bus system for intelligent sensors and actuators developed by Honeywell Inc., Micro Switch Division. The SDS specification covers physical layer and application layer. Smart Distributed System devices have advanced device-level functions, system and device diagnostics.
SERCOS (SErial Real-time COmmunications System) The standard (IEC-61491) for interfacing between controllers, digital servo drives, and I/O devices. The SERCOS interface is implemented with fiber optic cable that increases the reliability and noise-immunity of a multi-axis control system.
Serial Interface Relating to the electrical interconnection between the computer and peripheral units (for instance, a printer) in which data is transmitted 1 bit at a time over a single wire.
