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Introducing the Function Blocks
1-1
Introducing the Function Blocks
1-1-1
Overview and Features
4
The CX-Programmer Ver. 5.0 (and later versions) is a Programming Device
that can use standard IEC 61131-3 function blocks. The CX-Programmer
function block function is supported for CJ2H CPU Units, CP1H CPU Units,
NSJ-series NSJ Controllers, and FQM1 Flexible Motion Controllers as well as
CS/CJ-series CPU Units with unit version 3.0 or later and has the following
features.
• User-defined processes can be converted to block format by using func-
tion blocks.
• Function block algorithms can be written in the ladder programming lan-
guage or in the structured text (ST) language. (See note.)
• When ladder programming is used, ladder programs created with non-
CX-Programmer Ver. 4.0 or earlier can be reused by copying and past-
ing.
• When ST language is used, it is easy to program mathematical pro-
cesses that would be difficult to enter with ladder programming.
Note The ST language is an advanced language for industrial control
(primarily Programmable Logic Controllers) that is described in IEC
61131-3. The ST language supported by CX-Programmer con-
forms to the IEC 61131-3 standard.
• Function blocks can be created easily because variables do not have to
be declared in text. They are registered in variable tables.
A variable can be registered automatically when it is entered in a ladder or
ST program. Registered variables can also be entered in ladder programs
after they have been registered in the variable table.
• A single function block can be converted to a library function as a single
file, making it easy to reuse function blocks for standard processing.
• A program check can be performed on a single function block to easily
confirm the function block's reliability as a library function.
• Programs containing function blocks (ladder programming language or
structured text (ST) language) can be downloaded or uploaded in the
same way as standard programs that do not contain function blocks.
Tasks containing function blocks, however, cannot be downloaded in task
units (uploading is possible).
• One-dimensional array variables are supported, so data handling is eas-
ier for many applications.
Note The IEC 61131 standard was defined by the International Electro-
technical Commission (IEC) as an international programmable log-
ic controller (PLC) standard. The standard is divided into 7 parts.
Specifications related to PLC programming are defined in Part 3
Textual Languages (IEC 61131-3).
• A function block (ladder programming language or structured text (ST)
language) can be called from another function block (ladder programming
language or structured text (ST) language). Function blocks can be
nested up to 8 levels and ladder/ST language function blocks can be com-
bined freely.
Section 1-1
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