Omron SYSMAC C500 Installation Manual page 109

Rack PC
RAM
Remote I/O Unit
ROM
Special I/O Unit
system configuration
Unit
Glossary
A PC that is composed of Units mounted to one or more Racks. This
configuration is the most flexible, and most large PCs are Rack PCs. A Rack
PC is the opposite of a Package-type PC, which has all of the basic I/O,
storage, and control functions built into a single package.
[R(andom) A(ccess) M(emory)] RAM will not retain data when power is
disconnected. Therefore data should not be stored in RAM.
A Unit that extends the distance an Expansion I/O Rack can be from the
CPU.
[R(ead) O(nly) M(emory)] A type of digital storage that cannot be written to. A
ROM chip is manufactured with its program or data already stored in it, and it
can never be changed. However, the program or data can be read as many
times as desired.
A dedicated Unit that is designed for a specific purpose. Special I/O Units
include Position Control Units, High-Speed Counters, Analog I/O Units, etc.
The arrangement in which Units in a System are connected. This term refers
to the conceptual arrangement and wiring together of all the devices needed
to comprise the System. In OMRON terminology, system configuration is
used to describe the arrangement and connection of the Units comprising a
Control System that includes one or more PCs.
In OMRON PC terminology, the word Unit is capitalized to indicate any
product sold for a PC System. though most of the names of these products
end with the word Unit, not all do, e.g., a Remote Terminal is referred to in a
collective sense as a Unit. Context generally makes any limitations of this
word clear.
105