The MPrT button (Meldeprüftaste or indicator check button) is a DUS501 diagnostic tool. With it, the dispatcher can verify that the panel lights are working correctly.
Operation
Indicator Diagnostic Button
The button has three states:
normal
all OFF
all ON
Cycling through these states is accomplished by pressing MPrT together with the station button. Each time MPrT + station button are pressed, the diagnostic status changes. You will need to do this combination three times to return the panel to the normal state.
