Omron CS1W-SLK11-21 - 06-2004, Руководство пользователя

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Glossary
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Peripheral Device Devices connected to a PLC System to aid in system operation. Peripheral de-
vices include printers, programming devices, external storage media, etc.
peripheral servicing Processing signals to and from peripheral devices, including refreshing, com-
munications processing, interrupts, etc.
PID Unit A Unit designed for PID control.
polling The process whereby a device consecutively sends signals to other devices in
the same network to pass data back and forth, e.g., as in a data link.
present value The current value registered in a device at any instant during its operation.
Present value is abbreviated as PV. The use of this term is generally restricted
to timers and counters.
printed circuit board A board onto which electrical circuits are printed for mounting into a computer
or electrical device.
Programmable Controller A computerized device that can accept inputs from external devices and gen-
erate outputs to external devices according to a program held in memory. Pro-
grammable Controllers are used to automate control of external devices.
Although single-unit Programmable Controllers are available, building-block
Programmable Controllers are constructed from separate components. Such
Programmable Controllers are formed only when enough of these separate
components are assembled to form a functional assembly, i.e., there is no one
individual Unit called a PLC.
Programming Console The simplest form or programming device available for a PLC. Programming
Consoles are available both as hand-held models and as CPU-mounting mod-
els.
Programming Device A Peripheral Device used to input a program into a PLC or to alter or monitor
a program already held in the PLC. There are dedicated programming devices,
such as Programming Consoles, and there are non-dedicated devices, such
as a host computer.
PROM Programmable read-only memory; a type of ROM into which the program or
data may be written after manufacture, by a customer, but which is fixed from
that time on.
PROM Writer A peripheral device used to write programs and other data into a ROM for per-
manent storage and application.
prompt A message or symbol that appears on a display to request input from the op-
erator.
protocol The parameters and procedures that are standardized to enable two devices
to communicate or to enable a programmer or operator to communicate with a
device.
PV See present value .
Rack An assembly that forms a functional unit in a Rack PLC System. A Rack con-
sists of a Backplane and the Units mounted to it. These Units include the Pow-
er Supply, CPU, and I/O Units. Racks include CPU Racks, Expansion I/O
Racks, and I/O Racks. The CPU Rack is the Rack with the CPU mounted to it.
An Expansion I/O Rack is an additional Rack that holds extra I/O Units. An I/O
Rack is used in the C2000H Duplex System, because there is no room for any
I/O Units on the CPU Rack in this System.