# parameter

**URL:** <https://tech-community.robotics.abb.com/t/parameter/2247>\
**Category:** Robot Controller\
**Created:** [October 28, 2008, 10:09am UTC](https://tech-community.robotics.abb.com/t/parameter/2247 "2008-10-28T10:09:47Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![carmila](https://avatars.discourse-cdn.com/v4/letter/c/4bbf92/32.png) [@carmila](https://tech-community.robotics.abb.com/u/carmila)\
**Post date:** [October 28, 2008, 10:09am UTC](https://tech-community.robotics.abb.com/t/parameter/2247/1 "2008-10-28T10:09:47Z")

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hi, i heve a problem using parameter. I use then num type for save my parameter, but the value that I save to this num is gone when I start the program from main.  
Can I save a parameter always exist, wheter i move the PP to main or not? What data type that I should use?

Thanks before  
Carmila

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**Author:** ![j\_proulx](https://avatars.discourse-cdn.com/v4/letter/j/8c91f0/32.png) [@j\_proulx](https://tech-community.robotics.abb.com/u/j_proulx)\
**Post date:** [October 29, 2008, 10:05pm UTC](https://tech-community.robotics.abb.com/t/parameter/2247/2 "2008-10-29T22:05:27Z")

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Hello,  
You should make sure your num data is declared as a PERS persistant and not a VAR variable.

 

Variable characteristics

A variable contains a data value. If the program is stopped and started the variable keeps its

value, but if the program pointer is moved to main the variable data value is lost.

 

What is a persistent variable

A persistent variable is basically the same as an ordinary variable, but with one important

difference. A persistent variable remembers the last value it was assigned, even if the program

is stopped and started from the beginning again.

BR Jim Proulx

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<div class="post-metadata">

**Author:** ![carmila](https://avatars.discourse-cdn.com/v4/letter/c/4bbf92/32.png) [@carmila](https://tech-community.robotics.abb.com/u/carmila)\
**Post date:** [October 30, 2008, 4:44am UTC](https://tech-community.robotics.abb.com/t/parameter/2247/3 "2008-10-30T04:44:18Z")

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Dear Jim,

Thank you for your reply. it’s work. thank you. Finally I know the differences between var and pers (I don’t know the differences before).

Thank you:+1:

Carmila