How can I check for a proper serial connection?

Make sure the serial cable is securely connected to the COM port on your PC, and to the connector marked “PC RS232” on the LIN Tester. Make sure you use the cable provided with the hardware, or another serial cable with a DB9 female and a DB9 male connector, all pins connected directly. Next, in the PC software, go to Configuration/ Select COM port. Choose the proper port, and press OK. After initialization, the status line should read “Status: OK” or “Status: Stop”. In case of connection problems, it will read “Status: Error”. If you are running in offline-mode, it will read “Status: Off-Line”.