Function Block for Random Numbers

[Zeugwerker]

Hi,

I would like to generate random numbers in a PLC, is there a function block available to generate random numbers?

Thx in advance

[Zeugwerker · Accepted solution]

I found a library and an appropriate function block for my case:

CmpCrypto Implementation Library Documentation
Title: CmpCrypto Implementation
Version: 3.5.17.0
Author: CODESYS Development GmbH

with the function CmpCrypto_Implementation.CryptoGenerateRandomNumber(SIZEOF(u1), ADR(u1));

[CodeShepherd]

There is also a function RDM() in the OSCAT Basic library. See Codesys store for further information.

[TheCodeCaptain]

Hi,

as the implementation is a bit tricky, here is some example code.

PROGRAM PLC_PRG
VAR
	uiNumOfRandomBytes	:	UDINT	:=	4;
	Result				:	UDINT;
	udiRandom2			:	UDINT; // Random number
	bsRandomNumber : RtsByteString := (ui32MaxLen:=SIZEOF(uiNumOfRandomBytes), ui32Len:=0, pByData:=ADR(udiRandom2)); // 
END_VAR


// This code is working and generates a random number udiRandom2
Result	:=	CryptoGenerateRandomNumber(ui32NumOfRandomBytes:= uiNumOfRandomBytes, pRandom:= ADR(bsRandomNumber));