Lost connection to MySql Server during Query

Hello,

I use a MySql DataBase with Linux Server, and a Delphi development with DbExpress components
After a time of non use of the program, if I try to refresh information, an error message appears :
"Lost connection to MySql Server during Query"
Is there only a parameter on the mysql server to adjust
or is there a particular test under dbexpress to reactivate the connection ?

Thanks for a respons

Jacques LE GOHEBEL