L

.L5K

A file format used for text files imported and exported by the

Logix Designer

application. An .L5K file contains an ASCII representation of the data for an entire project and, when imported, creates a new project file or overwrites an existing project file. This is in contrast to the .CSV.

The file extension for this format must be .L5K; if you change the extension using a tool like the Windows Explorer, the

Logix Designer

application is not able to import this file.

.L5X

The .L5X file is structured using Extensible Markup Language (XML) tags. In addition to being able to open and modify the .L5X file in a text editor, such as Notepad, you can also view the contents of the file in Microsoft Internet Explorer and other tools that work with XML files.

You can import and export a project by exporting ladder rungs (including the referenced tags and data types), trends, User-defined Data Types, Add-On Instructions, programs, equipment phases, and routines to an .L5X file and importing it into the required project.

ladder diagram

An industry standard for representing relay control logic.

ladder element

The elements that make up your ladder diagram logic, including rungs, instructions, branches, and branch wires.

ladder logic

A program written in a format resembling a ladder-like diagram. A programmable controller to control devices uses the program.

leading-edge triggering

A programming technique of triggering some steps by means of an off-to-on transition of an input signal. The off-to-on transition is considered the leading edge of the input pulse.

least significant bit (LSB)

The bit that represents the smallest value within a string of digits.

least significant digit (LSD)

The digit that represents the smallest value within a string of digits.

LED

Light Emitting Diode. It is used as a status indicator for controller functions and inputs/outputs.

LIFO

Last-In-First-Out. The order in which data is entered into and retrieved from a file.

limit switch

An electrical switch actuated by some part and/or motion of a machine or equipment contacting the switch.

linear acceleration/deceleration (LAD)

A circuit that controls the rate at which a motor is allowed to accelerate to a set speed or decelerate to a zero speed. On most drives, this circuit is adjustable and can be set to accommodate a particular application.

Linear Positioning mode

An axis configuration parameter that provides a maximum total linear travel of 1 billion feedback counts. With this mode, the unwind feature is disabled and you can limit the linear travel distance traveled (by the axis) by specifying the positive and negative travel limits for the axis.

linear segment

A straight line between two cam points.

links

Links connect steps to transitions and transitions to steps. The direction of the link is always from the bottom of one element to the top of another element. Links have no runtime function other than defining the order of sequence elements.

A 64-bit SIN integer value used to store Alarms and Events time tags. The instructions that support LINT are GSV, SSV, COP, and CPS. Only the WallClockTime object is required to support the LINT data type.

Passing LINT to an Add-On Instruction, JSR, SBR, or RET will not support LINT data type.

In the Tag Editor, use the following

Style

settings to choose millisecond or nanosecond precision for time stamps for LINT data type tags:

See also data type

listen only rack optimization

An I/O connection where another controller owns/provides the configuration data for the module. A controller using a listen only connection does not write configuration. It can only establish a connection to the module when the owner controller is actively controlling.

local I/O

An I/O connected to a controller across a backplane or a parallel link, thus limiting its distance from the controller.

local scope

The scope of a declaration applying to only one program.

Local tag

For an Add-On Instruction, Local tags are used strictly by the instruction and not the user of the instruction. As such, Local tags are not available as members in the data structure when a tag is of the Add-On Instruction data type. Local tags are typically used for instructions internal to the Add-On Instruction or for tags that are used as retentive intermediate values in some operation. Local tags can be viewed only from within the Add-On Instruction definition.

lock tolerance

An axis configuration parameter that determines how close an axis must actually be, to the desired end position of a move, before the motion system may determine that the move is complete.

logic

A process of solving complex problems through the repeated use of simple functions that can be True or False. This is also a general term for digital circuits and programmed instructions to perform required decision making and computational functions.

logical address

See address.

logical model

A hierarchy (graphical tree) of programs and folders in the Logical Organizer that is organized in terms of procedures, objects, functions, equipment, or some other more natural term or concept; compare to the execution model displayed in the Controller Organizer.

Logical Organizer

The Logical Organizer is a graphical representation of the logical organization of your project. This window consists of a hierarchical tree of the programs and folders that contain all of the information about the programs in the current project. The Logical Organizer is a Tool Window that you can resize, undock, dock, and move.

low byte

Bits 0 through 7 of a word.

low nibble

The 4 least significant bits of a byte.

low pass filter

A digital device that provides noise rejection for input signals. This device is programmable and has eight filter frequency options for each channel. A low frequency provides the most noise rejection. A high frequency provides the least noise rejection and a faster step response time.