Random Number Generator in PM573.

Hello,

I am trying to simulat one project and try to generate rendom value between range.

Please suggest me any function/Function block/formula.

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Nirav Rank: 684

Asked 2 years ago

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AFAIK the random number is not a function available in Codesys...

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Flavio Mussolin AKS expert

Rank: 4

Answered 2 years ago

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I'm not sure if this helps, but library functions sometimes use a simple linear congruential generator for pseudo random numbers:

y" = (ay' + c) mod m

Check the Internet for details.

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Thomas Kruse Rank: 57

Answered 2 years ago

If you're trying to simulate a varying signal, then then an evenly spaced random number doesnt really work very well - you're better to use a gaussian RNG because this gives you a random number where the next number in the sequence is "sort of" similar to the previous one. This way you get a value that wanders randomly up and down.

However, RNG's arent really required to simulate anything usefull. You can get usefull results by just adding a +/- 0.5% of range sine wave to to the simulated signal value.

If you just want something simple and dont care that its predicatable ....

i = 7 * i `mod` 11

--- you can seed "i" with any value but the ms of current time works well.

https://cdsmith.wordpress.com/2011/10...

once you have a simple RNG you can make a gaussian RNG ( if you really want to go to the trouble)

http://www.design.caltech.edu/erik/Mi...

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