Omron SYSMAC LINK C1000H-SLK21-V1 System Manual page 160

input device
input point
input signal
instruction
interface
interrupt (signal)
ladder diagram (program)
ladder diagram symbol
ladder instruction
LAN
leading zero
least-significant (bit/word)
LED
leftmost (bit/word)
link
Link Adapter
Link Area
linkable slot
146
Glossary
An external device that sends signals into the PC System.
The point at which an input enters the PC System. Input points correspond
physically to terminals or connector pins.
A change in the status of a connection entering the PC. Generally an input signal
is said to exist when, for example, a connection point goes from low to high volt-
age or from a nonconductive to a conductive state.
A direction given in the program that tells the PC of the action to be carried out,
and the data to be used in carrying out the action. Instructions can be used to
simply turn a bit ON or OFF, or they can perform much more complex actions,
such as converting and/or transferring large blocks of data.
An interface is the conceptual boundary between systems or devices and usu-
ally involves changes in the way the communicated data is represented. Inter-
face devices such as NSBs perform operations like changing the coding, format,
or speed of the data.
A signal that stops normal program execution and causes a subroutine to be run
or other processing to take place.
A form of program arising out of relay-based control systems that uses circuit-
type diagrams to represent the logic flow of programming instructions. The
appearance of the program is similar to a ladder, and thus the name.
A symbol used in drawing a ladder-diagram program.
An instruction that represents the conditions on a ladder-diagram program. The
other instructions in a ladder diagram fall along the right side of the diagram and
are called terminal instructions.
An acronym for local area network.
One of one or more consecutive zeros in the leftmost digits of an address or
numeric value.
See rightmost (bit/word).
Acronym for light-emitting diode; a device used as for indicators or displays.
The highest numbered bits of a group of bits, generally of an entire word, or the
highest numbered words of a group of words. These bits/words are often called
most-significant bits/words.
A hardware or software connection formed between two Units. "Link" can refer
either to a part of the physical connection between two Units or a software con-
nection created to data existing at another location (i.e., data links).
A Unit used to connect communications lines, either to branch the lines or to con-
vert between different types of cable. There are two types of Link Adapter:
Branching Link Adapters and Converting Link Adapters.
A data area that is designed for use in data links.
A slot on either a Backplane to which a Link Unit can be mounted. Backplanes
differ in the slots to which Link Units can be mounted.