The programming cable PK3 is used to program the announcements into the voice modules SPL12 and SPL4. A USB 2.0 port is available on the PC side. A 4-pin Molex socket is used to connect to the voice module. In the plastic sleeve there is a circuit that converts the USB signal to a serial signal. This circuit is supplied from the voice module. For this reason, the PC only recognizes the programming cable when the voice module is supplied with voltage.