Omron CS1W-SLK11-21 - 06-2004 Manual page 191

rack number
Rack PLC
RAM
RAS
refresh
refresh parameter (table)
relay-based control
reserved bit
reserved word
reset
response code
response format
Restart Bit
restart continuation
retrieve
retry
rightmost (bit/word)
rising edge
ROM
174
Glossary
A number assigned to a Rack according to the order that it is connected to the
CPU Rack, with the CPU Rack generally being rack number 0.
A PLC that is composed of Units mounted to one or more Racks. This config-
uration is the most flexible, and most large PLCs are Rack PLCs. A Rack PLC
is the opposite of a Package-type PLC, which has all of the basic I/O, storage,
and control functions built into a single package.
Random access memory; a data storage media. RAM will not retain data when
power is disconnected.
An acronym for reliability, assurance, safety.
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 mem-
ory so that they agree with the status of inputs from external devices.
A table of settings that specifies which words in the data links for a System are
to be refreshed for a particular PLC. See common link parameter table.
The forerunner of PLCs. In relay-based control, groups of relays are intercon-
nected to form control circuits. In a PLC, these are replaced by programmable
circuits.
A bit that is not available for user application.
A word in memory that is reserved for a special purpose and cannot be access-
ed by the user.
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.
A code sent with the response to a data transmission that specifies how the
transmitted data was processed.
A format specifying the data required in a response to a data transmission.
A bit used to restart a Unit mounted to a PLC.
A process that allows memory and program execution status to be maintained
so that PLC operation can be restarted from the state it was in when operation
was stopped by a power interruption.
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 PLC is called a load.
The process whereby a device will re-transmit data which has resulted in an
error message from the receiving device.
The lowest numbered bits of a group of bits, generally of an entire word, or the
lowest numbered words of a group of words. These bits/words are often called
least-significant bits/words.
The point where a signal actually changes from an OFF to an ON status.
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