# "Realistic" function in Programable device simulator

**URL:** <https://forum.inductiveautomation.com/t/realistic-function-in-programable-device-simulator/94569>\
**Category:** Ignition\
**Tags:** ignition81\
**Created:** [August 13, 2024, 1:17am UTC](https://forum.inductiveautomation.com/t/realistic-function-in-programable-device-simulator/94569 "2024-08-13T01:17:15Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![miketob](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/miketob/32/5936_2.png) [@miketob](https://forum.inductiveautomation.com/u/miketob)\
**Post date:** [August 13, 2024, 1:17am UTC](https://forum.inductiveautomation.com/t/realistic-function-in-programable-device-simulator/94569/1 "2024-08-13T01:17:15Z")

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I have a doubt about the behavior of the "realistic" instruction in the device simulator.

The syntax is:  
**realistic(setPoint, proportion, integral, derivative, repeat)**

I understand the _setPoint_ and _repeat_ parameters, but, since I am not a PLC / Control guy I don't understand the Proportion, Integral and Derivative parameters.

I know there is a big therory behind those concepts, but I'd like to know if there are some general rules, or pointers, something like:

- X controls the variability or amplitude,
- Y controls the frecuency,
- Don't use a value greater than A for parameter B

Thank you