Technical data

The memory contains all the information that the programmer needs

to represent the function block graphically when it is called and to

check the operands during parameter assignment and programming of

the function block. The programmer rejects incorrect input.

When handling function blocks, distinguish between the following

procedures:

•• programming FB/FX

and

•• calling FB/FX and then assigning actual values to the parameters.

Distinction: "programming" –

"calling and assigning

parameters"

When programming, you specify the function of the block. You must

decide which input operands the function requires and which output

results it should transfer to the calling program. You define the input

operands and output results as formal operands. These function as

tokens.

When a block is

called by a higher order block (OB, PB, SB, FB, FX),

the formal operands (block parameters) are replaced by actual operands;

i.e.

parameters are assigned to the function block.

How to program

IF... THEN...

You want to program a function

block "directly", i.e. without

formal operands.

Program it as you would a

program or sequence block.

You want to use formal operands

in a function block.

Proceed as explained on the

following pages.

Make sure you keep to the

required order:

First program the FB/FX with the

formal operands and keep it on

the PG (offline) or in the CPU

memory (online)

Then program the block(s) to be

called with the actual operands.

Function Blocks

CPU 928B Programming Guide

C79000-B8576-C898-01

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