FB having single input but initialized with Array

2024-05-07T06:31:40.149000Z

Why will it retain the sum value from the last call?

This is how PLC work. Usually variables only get initialized after a download or a reset (i.e. power loss).

RETAIN variables are saved in a special kind of RAM and keep their value after a power loss.

To initialize variables on every call of your FB use the VAR TEMP block.

VAR_TEMP
    sum : INT;
END_VAR

FB having single input but initialized with Array

2024-05-06T12:08:38.336000Z

Ok yes now the loop has stopped when I set sum to zero before the for loop.
Why will it retain the sum value from the last call?

FB having single input but initialized with Array

2024-05-06T12:08:31.529000Z

Ok yes now the loop has stopped when I set sum to zero before the for loop.
Why will it retain the sum value from the last call?

FB having single input but initialized with Array

2024-05-06T06:34:06.093000Z

with every call of the FB500 it keeps adding the INTs of the array to the sum variable.
set sum to 0 before you start the loop.

FB having single input but initialized with Array

2024-05-04T18:25:09.410000Z

https://ibb.co/k3DhkZT

FB having single input but initialized with Array

2024-05-03T08:33:33.342000Z

**Guys I am new to codesys. Here the FB MyMovingAvg has a single Input ( nextNum: INT;) However in the main program this FB has been initialized with an ARRAY of INT

Is this, Ok? and how will it access the next elements of the Array? **

Will more code will need to be written in the main program to make it able to get rest of the elements of array?
Basically this is an example of dynamic memory

FUNCTION_BLOCK MyMovingAvg
VAR_INPUT
    nextNum: INT;
END_VAR
VAR_OUTPUT
    avg: REAL;
END_VAR
VAR
    windowPtr: POINTER TO INT; // pointer to the first array element. You can access other elements with [] as usual (up to windowSize)
    windowSize: DINT;
    currentIndex: UINT;
END_VAR

METHOD FB_Init: BOOL
VAR_INPUT
    bInitRetains: BOOL;
    bInCopyCode: BOOL;
END_VAR
VAR_IN_OUT // basically REFERENCE TO
    window_buffer: ARRAY [*] OF INT; // array of any size
END_VAR

THIS^.windowPtr := ADR(window_buffer);
THIS^.windowSize := UPPER_BOUND(window_buffer, 1) - LOWER_BOUND(window_buffer, 1) + 1;

// usage:
PROGRAM Main
VAR
    avgWindow: ARRAY [0..123] OF INT; // whatever size you want!
    movAvg: MyMovingAvg(window_buffer := avgWindow);
END_VAR

movAvg(nextNum := 5);
movAvg.avg;

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FB having single input but initialized with Array

FB having single input but initialized with Array

FB having single input but initialized with Array

FB having single input but initialized with Array

FB having single input but initialized with Array

FB having single input but initialized with Array