R

ramp rate

The rate of change of a given parameter. It defines the maximum rate of change an output is allowed to transition.

read

To acquire data from a storage place. For example, the controller reads information from the input data file to solve the ladder program.

Real

A basic data type (stored in a floating, IEEE single-precision, 32-bit format) that can be used to define a variable, a program, or a device.

real time sample (RTS)

A programmed interval at which updated information is supplied to the processor. It is a method by which data is gathered, at precise intervals, for use by the processor.

redundancy

The use of multiple similar devices, such that if one fails, the remaining device(s) take over the assigned functions, thus improving the devices' availability.

redundancy state

The state of a redundant chassis pair that indicates which chassis is handling the assigned functions. In a dual redundancy system, two redundancy states exist. Within ICP redundancy, these two states are Primary and Secondary.

redundant chassis pair (RCP)

Within the ICP dual redundancy system, redundancy is supported at the chassis level only, and then only for certain modules. A pair of chassis configured for redundant operation is called a redundant chassis pair, or RCP. This RCP may or may not have control functions (that is, it may consist only of communications modules).

reference

The use of a tag somewhere in the controller as an operand in an instruction or expression, or as an alias.

reference frame

An imaginary Cartesian coordinate system used to define a Cartesian origin and reference orientation.

In the MCT and MCTP transformation motion instructions, the MCT's and MCTP's Orientation operand specifying the Rotation Vector for Kinematics transformations changed from previous releases to apply Rotation ordering first about X, then Y, then Z. (The prior Rotation ordering was first about Z, then Y, then X.) This change impacts the Initial position of any MCT or MCTP using 2Dimension, 2D, or 3D Rotation vector. A 1D Rotation is not affected.

registration position

An axis position that is captured in dedicated hardware at the instant a registration input is triggered. This can be used during calibration and synchronization of axes with real world positions.

relay logic

A representation of the program or other logic in a form normally used for relays.

REM Program mode

A remote program mode where the controller keyswitch is in Remote, logic is not executing, I/O is not controlled and editing operations are available. This mode can be changed remotely.

REM Run mode

A remote run mode during which the controller scans or executes the ladder program, monitors input devices, energizes output devices and acts on enabled I/O forces.

REM Test mode

A controller mode, similar to run mode, in which output modules are commanded to their program mode. Test mode is not available on the keyswitch, so the controller keyswitch must be in Remote.

remote I/O

The I/O connected to a processor across a serial link. With a serial link, the remote I/O can be located long distances from the processor.

remote I/O link

A serial link for carrying I/O data between a PLC or SLC processor/scanner and remote I/O adapters.

remote I/O scanner

A separate module (of a multi-module PLC processor) or a built-in component (of a single-module PLC processor) that provides communication with remote I/O adapters across a remote I/O link.

remote mode selection

A feature that lets you select or change processor modes of operation with a peripheral device from a remote location.

remote programming

The programming from a distant location by communicating across a network.

remote termination block (RTB)

It is a customer wiring option. The customer field wire is run to the RTB instead of directly to the module terminal block. The RTB then provides pre-wired connections to the module terminal block. The RTB offers a built-in Cold Junction Sensor and an isothermal bar to ensure all terminals are at the same temperature for more accurate cold junction compensation. For applications requiring higher accuracy, use an RTB for improved cold junction performance.

removable terminal block (RTB)

A field wiring connector for input and output modules.

replace zone (R rung)

An edit zone that signifies a rung that has been replaced by an insert zone because of a change made while in Run mode. The rung is only executed in Untest Edits mode. The rung cannot be edited.

report

An application data printout containing information you choose.

request to send (RTS)

A request from the module to the modem to prepare for transmission. It typically turns on the data carrier.

requested packet interval (RPI)

The amount of time (in milliseconds) between updates of data from the remote controller. This value is scaled as a real value from the microseconds stored in the controller. The local controller will receive data at least this fast.

reserved bit

A status file location to which you should not read or write.

resolution

The smallest distinguishable increment into which a quantity can be devised (for example, position or shaft speed). This can also refer to the degree to which nearly equal values of a quantity can be distinguished.

For rotary encoders, this is the number of unique electrically identified positions occurring in 360 degrees of input shaft rotation.

resolver

A transducer using magnetic coupling to measure absolute rotary position (within one revolution). It generates an analog output and requires special conditioning electronics.

restore

To download (transfer) a program from a personal computer to a controller.

retentive data

The information associated with data files (timers, counters, inputs, and outputs) in a program that is preserved through power cycles regardless of the state of the controller.

retentive output instruction

A rung-output instruction that sets the state of the output only when the rung is true. Whenever the rung is not true, it does not control the state of the output.

retry

The repeat attempt to send a transmission from one point to another. A retry is executed when the original transmission is unsuccessful. Retries are executed repeatedly until the transmission is successful or a maximum limit is reached.

revision

The major and minor revision of the controller separated by a period.

rise time

The time it takes to raise an analog voltage or current output level from 10% to 90% of maximum.

Rotary Positioning mode

A mode that enables the rotary unwind capability of the axis. This feature provides infinite position range by unwinding the axis position whenever the axis moves through a complete unwind distance. The number of encoder counts per unwind of the axis is specified by the Position Unwind attribute.

routine

A sequence of logic that is executed as a block.

RS-232

An EIA standard that specifies electrical, mechanical, and functional characteristics for serial binary communication circuits. A single-ended serial communications interface.

RS-232-C

An EIA standard that specifies electrical, mechanical, and functional characteristics for serial binary communication circuits in a point-to-point link.

RS-422

An EIA standard that specifies electrical characteristics of balanced-voltage digital interface circuits in a point-to-point link.

RS-423

An EIA standard that specifies electrical characteristics of unbalanced-voltage digital interface circuits in a point-to-point link.

RS-449

An EIA standard that specifies mechanical and functional characteristics for digital interface circuits. This standard is used in combination with RS-422 or RS-423.

RS-485

An EIA standard that specifies electrical characteristics of balanced-voltage digital interface circuits in a multi-point link.

rung

The composition of ladder logic. Ladder logic is comprised of a set of rungs. A rung is made up of several components, which are:

In addition, the area to the left of the power rail is called the rung selection region.

The last rung in a routine is called the End rung. This rung contains no instructions and its rung number is "End." By default, this rung is black, though you can change it. This rung is not actually part of your routine. It symbolizes the end of the routine. You cannot complete any editing functions if you are located on this rung.

During Run mode, the inputs on a rung are evaluated to be True or False. If a path of true logic exists, the outputs are made True; if all paths are false, the outputs are made False.

rung comment

The information pertaining to the rung. You can add rung comments to your rungs. Each rung contains its own comment. For an online editing rung pair, all the rungs of the pair share the same comment.

The width and height of the rung comment is limited. If the text of the comment is wider than the rung, the text will be either wrapped or clipped. The maximum number of lines that can be displayed is 1000. If the comment exceeds this length, it will be clipped. You can also adjust this number so that fewer lines display.

rung number

The sequential numbering of rungs in ascending order from 0 to n. The numbers appear in the rung selection region.

rung selection region

The area in which you can select a rung, and the area in which the selection for the rung is displayed.

rung state indicator

Indicates the type or state of the rung. This information is displayed in the rung selection region. The valid states are:

rung wire

An element on which instructions and branches are placed. The rung wire connects all instructions and branch objects.