Use of function blocks in Omron PLC programming software - Database & Sql Blog Articles

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Omron plc programming software has also added function blocks for programming function blocks. The function blocks function in accordance with IEC61131–3.

An example of a function block calling a ladder diagram

The main purpose of using function blocks is to promote good structured programming, function calls; to make complex programs create less code and easier to manage programs.

A function block consists of a block header and a block

Block header - the data to be used in the function block program: as a variable for the connection of the input and output, the internal variable of the function block, defined with the local parameters in the block - the formal parameter.

The block contains the possible instructions, the algorithm - this is the actual code each time the function block is executed. In the call, the corresponding input and output variables are substituted with the actual corresponding variables. Not all PLCs can create function blocks.

Function blocks Omron plc: CJ1M, CJ, CS, CP1H/L, etc. can be established;

The number of function blocks that each type of PLC can create is different. Up to 64 function blocks can be defined in the PLC, and up to 30,000 statements can be written.

Steps to create and use function blocks

First, the PLC must be a valid PLC type.

Second, the definition of the function block is created. Select the appropriate function block type: Ladder or Structured Text; a new function block is created and its name will default to 'Function Block'.

Third, open the function block for editing, including setting the function block variable in the block header; the block body is written using the written algorithm function block ladder structure editor or text editor.

Fourth, the created function block can be called in the main program ladder editor.

If a specific function block already exists, it can be selected from the 'FB list'. If not, the created function block only needs to enter a new name and select the appropriate 'FB List' definition. The selected function block is automatically created in the global symbol table (including the memory allocated for each variable defined in the function block header); the call of the function block is displayed in the ladder diagram.
The execution of the called function block can be connected to the function block EN input pin by executing the condition. When the execution condition is satisfied (equivalent to True), the energy flow reaches the EN pin and the function block is executed. The function block ENO output pin is optional. It can also be unselected; the execution coil or execution condition can be connected, but the rightmost element must be terminated with a coil or indication.

5. Connect the input and output pins of the function block.

These pins must be connected using the [Enter] key or from the [Function Block Parameters] option of the [Insert] menu; they cannot be connected with contacts or coils. The left side of the function block is the input pin; the right side is the output pin of the function block. The input and output pin connections for this function block are completely optional.

6. After the setup is complete, the CX–P program can be compiled, downloaded, and run.

Way of establishing

Select [Function Block] in the tree menu, right-click or select [Function Block] in the tree menu, and select [Function Block] from the drop-down menu [Insert].

There are several forms of creation

One is to import (suffix .CXF) existing function blocks directly from the file;
The second is to create it yourself: write it in structured text; or write it in ladder diagram.

Call method

Select the appropriate cell in the programming area, right click, or use the [Function Block Call] option from the [Insert] menu.