---

GLOSSARY
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 coordinating
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. A logical operator that requires all input conditions to be logic 1 for the output
to be logic 1. If any input is logic 0, then the output will

---

---

Çok teşekkürler

---

Başa dön