478 terms ch 03

a logical operator that requires all input conditions to be
a logic 1 for the output to be logic 1.

logical operators, such as AND, OR, NAND, NOR,
NOT and XOR, that can be used singly or in combination to form logical
statements.

a set of symbols used to express the
control program through conventional relay symbols.

a circuit having two or more input terminals and one
output terminal, where an output is present only when the prescribed inputs are
present.

any connected equipment, such as control
devices or peripheral devices, that supplies information to the CPU.

a program output that does not drive a
field device and is used for internal purposes only. It provides interlocking
functions like a hardwired control relay.

a set of symbols and rules for representing and
communicating information between people and machines.

the use of binary logic so that logic 0
represents the voltage level normally associated with logic 1.

a relay contact pair that is close when
the coil of the relay is not activated and open when the coil is activated.

a relay contact pair that is open when the
coil of the relay is not activated and closed when the coil is activated.

any connected equipment, such as control
devices or peripheral devices, that receives information or instructions from
the CPU.

a circuit in which two or more of the
connected components or contact symbols in a letter program are connected to
the same pair of terminals so that current may flow through all branches.

the conventional use of binary logic in
which logic 1 represents a positive logic level.

a letter program term that refers to the programmed
instructions that drive one output.

a circuit in which the components or
contact symbols are connected end to end.

a table that shows the state of a given output
as a function of all possible input combinations.