Hello,

thank You all for the answers.

DataMiser:
In each tick I'm checking File.Exists. Then File.GetLastWriteTime if time is different than time stored in memory, code is executed.
I'll try to use File system watcher - to be honest I even didn't know this function


David:
from the beginning I had set up time between tick to 30sec. Unfortunately always getting system error after 1000 ticks

Hannes:
SELECT Field1, Field2, Field3 FROM " & Filename, mycn <- also didn't helped


I was trying to do something else that partially solved my problem I'm using now dataAdapter instead dataReader and I'm not closing/disposing connection and dataAdapter.
At this moment application runs more than 6000 data reads, but I'm afraid that a the end I'll have problems with lack of memory...

Thank You