U

unicast

Message sent to a single network address.

Unit ID

An integer value representing the equipment unit the sequence is coordinating. The Unit ID is configured on the

Sequence Properties Dialog Box

,

Configuration

tab.

unscheduled programs

A collection of programs that are not scheduled by any task. They do not execute.

unwind

Unwind provides infinite position range to a rotary axis by returning axis position to a starting value without backward axis motion. The Unwind value is the distance in feedback counts for a rotary axis that is added or subtracted to the axis position to maintain the position within a specified range.

update time

The time between updates to the memory in the analog module of the digital value representing the analog input signal. (For analog inputs.)

OR

The time from the digital value being received at the analog module to when the analog output signal corresponds to it. (For analog outputs.)

upload

When data is transferred to a programming or storage device from another device. In

Logix Designer

specifically, it means to transfer or copy a control program from the controller to the

Logix Designer

application running on your PC.

upload merge

When you upload into an existing project file, documentation in the project file is merged with project components and logic (for example, rungs) uploaded from the controller. This is referred to as Upload Merge.

At the end of the Upload Merge, any documentation not associated with a component or with logic is deleted. Because of this automatic deletion of unused documentation,

Logix Designer

will not allow you to upload over an existing file unless it matches the controller. Otherwise, all of the documentation would be unused and therefore deleted.

In the event that you do not have a matching project file,

Logix Designer

allows you to create a new project file into which you can upload.

upper nibble

The four most significant bits of a byte.

usage

The tag property that identifies the parameter type. Examples of possible values are Local, Input, Output, InOut, Public.

user-defined data type (UDT)

A structured data type that is defined during the development of an application.