PLC_Glossary - Glossary Glossary of Terms used in...

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1 Glossary 1-800-752-8398 Glossary of Terms used in Programmable Controller-based Systems From Industrial Text and Video Co. the leader in Electrical, Motor Control and PLCs Video Training Programs
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2 Glossary 1-800-752-8398 G LOSSARY AC/DC I/O interface. A discrete interface that converts alternating current (AC) voltages from field devices into direct current (DC) signals that the processor can use. It can also convert DC signals into proportional AC voltages. action. A set of control instructions prompting a PLC to perform a certain control function during the execution of a sequential function chart step. acyclic message. An unscheduled message transmission. A/D. See analog-to-digital converter . address. (1) The location in a computer’s memory where particular information is stored. (2) The alphanumeric value used to identify a specific I/O rack, module group, and terminal location. addressability. The total number of devices that can be connected to a network. address field. The sequence of eight (or any multiple of eight) bits immediately following the opening flag sequence of a frame, which identifies the secondary station that is sending (or is designated to receive) the frame. AI. See artificial intelligence . algorithm. A set of procedures used to solve a problem. alphanumeric code. A character string consisting of a combination of letters, numbers, and/or special characters used to represent text, commands, numbers, and/or code groups. ambient temperature. The temperature of the air surrounding a device. American National Standards Institute (ANSI). A clearinghouse and coordinat- ing agency for voluntary standards in the United States. American Wire Gauge (AWG). A standard system used to designate the size of electrical conductors. Gauge numbers have an inverse relationship to size; larger gauges have a smaller diameter. analog device. An apparatus that measures continuous information signals (i.e., signals that have an infinite number of values). The only limitation on resolution is the accuracy of the measuring device. analog input interface. An input circuit that uses an analog-to-digital converter to translate a continuous analog signal, measured by an analog device, into a digital value that can be used by the processor. analog output interface. An output circuit that uses a digital-to-analog converter to translate a digital value, sent from the processor, into an analog signal that can control a connected analog device. analog signal. A continuous signal that changes smoothly over a given range, rather than switching suddenly between certain levels as discrete signals do. analog-to-digital converter (A/D). A device that translates analog signals from field devices into binary numbers that can be read by the processor. AND.
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PLC_Glossary - Glossary Glossary of Terms used in...

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