Glossary
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DM Area. Area addresses are prefixes with E and only words can be accessed.
The EM Area is separated into multiple banks.
EM card A card mounted inside certain PCs to added an EM Area.
EPROM Erasable programmable read-only memory; a type of ROM in which stored data
can be erased, by ultraviolet light or other means, and reprogrammed.
error code A numeric code generated to indicate that an error exists, and something about
the nature of the error. Some error codes are generated by the system; others
are defined in the program by the operator.
Error Log Area An area in System DM that is used to store records indicating the time and nature
of errors that have occurred in the system.
event processing Processing that is performed in response to an event, e.g., an interrupt signal.
exclusive NOR A logic operation whereby the result is true if both of the premises are true or both
of the premises are false. In ladder-diagram programming, the premises are
usually the ON/OFF states of bits, or the logical combination of such states,
called execution conditions.
exclusive OR A logic operation whereby the result is true if one, and only one, of the premises
is true. In ladder-diagram programming the premises are usually the ON/OFF
states of bits, or the logical combination of such states, called execution condi-
tions.
execution condition The ON or OFF status under which an instruction is executed. The execution
condition is determined by the logical combination of conditions on the same in-
struction line and up to the instruction currently being executed.
execution cycle The cycle used to execute all processes required by the CPU, including program
execution, I/O refreshing, peripheral servicing, etc.
execution time The time required for the CPU to execute either an individual instruction or an
entire program.
Expansion CPU Rack A Rack connected to the CPU Rack to increase the virtual size of the CPU Rack.
Units that may be mounted to the CPU Backplane may also be mounted to the
Expansion CPU Backplane.
Expansion Data Memory Unit A card mounted inside certain PCs to added an EM Area.
Expansion I/O Rack A Rack used to increase the I/O capacity of a PC. In CV-Series PC, either one
Expansion I/O Rack can be connected directly to the CPU or Expansion CPU
Rack or multiple Expansion I/O Racks can be connected by using an I/O Control
and I/O Interface Units.
extended counter A counter created in a program by using two or more count instructions in suc-
cession. Such a counter is capable of counting higher than any of the standard
counters provided by the individual instructions.
extended timer A timer created in a program by using two or more timers in succession. Such a
timer is capable of timing longer than any of the standard timers provided by the
individual instructions.
FA Factory automation.
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