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Glossary
485
main program All of a program except for the subroutines.
masking ‘Covering’ an interrupt signal so that the interrupt is not effective until the mask is
removed.
Master Short for Remote I/O Master Unit.
memory area Any of the areas in the PC used to hold data or programs.
mnemonic code A form of a ladder-diagram program that consists of a sequential list of the in-
structions without using a ladder diagram. Mnemonic code is required to input a
program into a PC when using a Programming Console.
MONITOR mode A mode of PC operation in which normal program execution is possible, and
which allows modification of data held in memory. Used for monitoring or debug-
ging the PC.
most-significant (bit/word) See
leftmost (bit/word).
NC input An input that is normally closed, i.e., the input signal is considered to be present
when the circuit connected to the input opens.
nest Programming one loop within another loop, programming a call to a subroutine
within another subroutine, or programming an IF-ELSE programming section
within another IF-ELSE section.
Net Link System An optical LAN formed from PCs connected through Net Link Units. A Net Link
System also normally contains nodes interfacing computers and other periph-
eral devices. PCs in the Net Link System can pass data back and forth, receive
commands from any interfaced computer, and share any interfaced peripheral
device.
Net Link Unit The Unit used to connect PCs to a Net Link System. The full name is “SYSMAC
Net Link Unit”.
Network Service Board A device with an interface to connect devices other than PCs to a Net Link Sys-
tem.
Network Service Unit A Unit that provides two interfaces to connect peripheral devices to a Net Link
System.
node One of the positions in a LAN. Each node incorporates a device that can commu-
nicate with the devices at all of the other nodes. The device at a node is identified
by the node number. One loop of a Net Link System (OMRON’s LAN) can consist
of up to 126 nodes. Each node is occupied by a Net Link Unit mounted to a PC or
a device providing an interface to a computer or other peripheral device.
NO input An input that is normally open, i.e., the input signal is considered to be present
when the circuit connected to the input closes.
noise interference Disturbances in signals caused by electrical noise.
nonfatal error A hardware or software error that produces a warning but does not stop the PC
from operating.
normal condition A condition that produces an ON execution condition when the bit assigned to it
is ON, and an OFF execution condition when the bit assigned to it is OFF.