I - N

identifier

A unique word used to represent a variable or a constant expression in a program.

Instruction List (IL)

One of the five programming languages defined by the IEC 61131-3 standard for programmable logic controllers. This language was deprecated in the third edition (current) of the standard.

initial situation

Set of the initial steps which represents the context of the program when it is started.

initial step

The logical start of a sequential function chart (SFC).

initial value

Value which has a variable when the virtual machine (application) starts the execution of the controller. The initial value of a variable can be the default value, a value given by the user when the variable is defined or the value of the retained variable after the virtual machine has stopped.

input

The direction of a variable or a device. An input variable is connected to an input channel of an input device.

input parameter

Input argument of a function or a function block. These parameters can only be read by function or function block. A parameter is characterized by a type.

instance of a function block

A copy of the internal data of a function block that persists from one call to the other. This word is used, by extension, to say that a program calls a function block instance and not the function block itself.

instruction

A mnemonic and data address defining an operation to be performed by the controller. A rung in a program consists of a set of input and output instructions. The input instructions are evaluated by the controller as being True or False. In turn, the controller sets the output instructions to True or False.

integer (INT)

An atomic data type consisting of a word used to store a 16-bit signed integer value (-32,768 to +32,767).

internal variable

A variable that is not linked to an input or output device.

internal binding list

The view displaying the resource links and internal variable bindings defined for a project.

I/O binding

A virtual connection between two software elements.

I/O complex device

Element grouping several simple I/O (input and output) devices. This provides the means for manufacturers to mix types and directions. The implementation of the I/O driver of an I/O complex device corresponds to the implementation of the drivers of all contained I/O simple devices. OEM parameters enable providing parameters to I/O complex devices.

I/O device

Element grouping several channels of the same type and direction. These can be either an I/O Simple Device or an I/O Complex Device.

I/O simple device

An I/O simple device corresponds to a piece of equipment having inputs or outputs, such as an I/O board. OEM parameters enable providing parameters to I/O simple devices. Integrators define I/O simple devices.

I/O variable

A variable connected to an input or output device. An I/O variable must be connected on a channel of an I/O device.

I/O wiring

Definition of the links between the variables of the Project and the channels of the I/O devices existing on the Target system.

jump

A change in the normal sequence of program execution by executing an instruction that alters the program counter (sometimes called a branch). In ladder programs, a JUMP (JMP) instruction causes execution to jump to a labeled rung.

keywords

Terms that have special meanings in a programming language. These terms are reserved and cannot be used as user-defined identifiers for variables, routines, or other elements.

label

The identifier for an instruction within a program. Labels can also be used for jump operations.

ladder diagram

An industry standard for representing relay control logic.

literal

A value that is expressed as itself rather than as a variable's value or the result of an expression.

local scope

The scope of a declaration applying to only one program.

locked I/O

Input or output variable, disconnected logically from the corresponding I/O device, by a "lock" command.

long integer (LINT)

Signed integer 64-bit format. Basic type that can be used to define a variable, a parameter, or a device.

long real (LREAL)

Type of a variable, stored in a floating IEEE double precision 64-bit format. Basic type that can be used to define a variable, a parameter, or a device.

long word (LWORD)

Unsigned long word 64-bit format. Basic type that can be used to define a variable, a parameter, or a device.

modifier (IL)

Single character put at the end of an IL operation keyword, which modifies the meaning of the operation.