Expect the program to indicate that the transceiver is receiving bytes despite there being no optical signal into the photodiode. Repeat the process to determine the lowest numbered sensitivity setting which gives no data received when there is no optical signal. Using other software. A terminal program is required for this test. Telix or a similar package which supports 115200 baud is preferable, but software such as Windows Terminal is sufficient for testing at lower data rates.
Higher speeds cause a higher laser duty cycle, making the beam reflection easier to see.
Move and rotate the reflective object until these characters are displayed correctly on the computer screen as the transceiver converts the characters to light, then converts the reflected light back into electrical signals which it returns to the computer. If the reflector directs too much of the laser beam back to the photodiode, the receiver will overload and no data will be displayed. If the reflector returns too little of the beam, then either no data or incorrect data will be displayed. Remove the reflective object from the laser path. Adjust the laser focus to give minimum spot size on an object at least 10 metres away.