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Glossary
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R
Term
Definition
rack-optimized connection
For digital I/O modules, you can select rack-optimized communication. A rack-optimized connection
consolidates connection usage between the controller and all the digital I/O modules in the chassis (or
DIN rail). Rather than having individual, direct connections for each I/O module, there is one
connection for the entire chassis (or DIN rail).
See direct connection.
remote connection
A connection to a module in a remote chassis or DIN rail. Communication requires a communication
module and/or adapter.
requested packet interval (RPI)
When communicating over a the network, this is the maximum amount of time between subsequent
production of input data.
• Typically, this interval is configured in microseconds.
• The actual production of data is constrained to the largest multiple of the network update time
that is smaller than the selected RPI.
routine
A set of logic instructions in a single programming language, such as a ladder diagram. Routines
provide the executable code for the project in a controller (similar to a program file in a PLC or SLC
controller).
S
Term
Definition
scheduled connection
A scheduled connection is unique to ControlNet communication. A scheduled connection lets you send
and receive data repeatedly at a predetermined rate, which is the requested packet interval (RPI). For
example, a connection to an I/O module is a scheduled connection because you repeatedly receive
data from the module at a specified rate. Other scheduled connections include connections to:
• communication devices.
• produced/consumed tags.
On a ControlNet network, you must use RSNetWorx for ControlNet software to enable all scheduled
connections and establish a network update time (NUT).
software version
The product ID label of a software products identifies the software version. This version denotes the
functional version of the software. The software version is usually two numbers separated by a period.
For example, in software version 10.02, the first number (10) defines the major revision and the second
number (02) defines the minor revision.
See firmware revision.
state machine
A state machine:
• calls the maine routine (state routine) for an acting state.
• manages the transitions between states with minimal coding.
• makes sure that the equipment goes from state to state along an allowable path.
state model
A state model divides the operating cycle of your equipment into a series of states. Each state is an
instant in the operation of the equipment. It's the actions or conditions of the equipment at a given
time.
structure
Some data types are a structure.
• A structure stores a group of data, each of which can be a different data type.
• Within a structure, each individual data type is called a member.
• Like tags, members have a name and data type.
• You create your own user-defined structure, using any combination of individual tags and most
other structures.
• To copy data to a structure, use the COP instruction.
system overhead timeslice
Specifies the percentage of controller time (excluding the time for periodic tasks) that is devoted to
communication and background functions (system overhead).
Publication 1756-RM094C-EN-P - June 2007