Please Help!

Usually in a Windows application, the app doesn't do anything until the user clicks a button or selects a menu option. So you would display your form with a textbox and allow the user to enter some text, then he or she would click a button to trigger some action. If you set the button's Default property to True, the user can trigger the button by pressing Enter. You may also with to disable the button at design time and enable it in the textbox's Change event only if the textbox contains text.

There are a number of events that you can code for, including Keypress and Change, that will be triggered if the user types in the text box.

As its name implies, the Change event fires whenever the text in a textbox changes. There's no way to configure it to behave differently. Instead, put code in the Change event procedure to handle only the text in which you're interested.

Lostfocus or Validate will only occur when another control gets the focus, so that won't help you.

As Phil suggested, use the Change event, combined with if statements, ie. if text1.text = "whatever" then ...,where whatever is the string(s) that you referred to.

Maybe what you are trying to do could be done with a simple button or checkbox?

Are the RFID codes a consistent length? If so, you can use the Len function in the Change event to check the number of characters in the textbox, and kick off your code when the text reaches the desired length.

If the codes are not a consistent length, start a Timer when the first character arrives, then process the text a short time (e.g. 0.5 seconds) later.