Omron SYSMAC C200HW-PCS01-EV1, Руководство по эксплуатации

Страница: 251 / 261

Glossary
235
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 PC System. A Rack consists
of a Backplane and the Units mounted to it. These Units include the Power Sup-
ply, 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.
RAM Random access memory; a data storage media. RAM will not retain data when
power is disconnected.
RAS An acronym for reliability, assurance, safety.
refresh The process of updating output status sent to external devices so that it agrees
with the status of output bits held in memory and of updating input bits in memory
so that they agree with the status of inputs from external devices.
relay A point in a network through which communications pass to reach another net-
work.
remote In network communications, the node or device with which communications are
taking place. See local.
remote node In network communications, the node with which communications are taking
place. See local node.
reset The process of turning a bit or signal OFF or of changing the present value of a
timer or counter to its set value or to zero.
response code A code sent with the response to a data communications command that speci-
fies how the transmitted data was processed.
response format A format specifying the data required in a response to a data transmission.
Restart Bit A bit used to restart a Unit mounted to a PC.
retrieve The processes of copying data either from an external device or from a storage
area to an active portion of the system such as a display buffer. Also, an output
device connected to the PC is called a load.
retry The process whereby a device will re-transmit data which has resulted in an
error message from the receiving device.
ROM Read only memory; 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 can never
be changed. However, the program or data can be read as many times as
desired.
router A device used to connect two networks (i.e., two coaxial cables) in an Ethernet
System.
routing table Tables of setting that specify what networks a device is a member of and what
nodes must be passed through to reach other specific networks. See local net-
work table and relay network table.