Under the following conditions timeouts can occur:

If the user doesn’t use the application for 30 minutes, he or she will be taken to login screen. The same thing will happen if the application is restarted on the server.

If an editable screen is open for more than 10 minutes. Then the edit mode will be canceled and user taken to previous screen.

Both times are default values and can be configured as needed through the Field Portal Configuration utility.