IAI America REXT - Manual (Page 209)


Part 1 Specification
Chapter 3 Gateway R unit
185
Part 1 Specification
(2) Function Block Configuration
A function block consists of a predetermined function block definition and an instance that actually places the function
block definition in a program.
[1] Function block definition
A program described in a function block. An algorithm is described along with a variable definition.
z Algorithm
A typical circuit defined by variable names (not actual addresses).
z Variable definition
A table describing the types (input, output or internal) and attributes (data type, etc.) of variables.
<Example of Function Block Definition>
[2] Instance
To actually use a function block in a program, a copy of its function block definition must be created and placed in the
program.
An instance is a function block definition placed in a program.
A function block definition represents a function block not yet placed in a program and therefore not yet assigned to a
memory (still in an abstract form). Once the function block is placed in a program and assigned to a memory (in a
tangible form), it is called an instance.
Instances are managed by their names. Use the same internal variables for instances of the same name, and use
different internal variables for those of different names.
1. Algorithm
2. Variable definition
Type
Internal
Internal
Input
Input
Variable name Type
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