wat is te usb slave connection on a cp1000c plotter

[Patrick4002]

Hello, i have a standard horizon cp1000c plotter and on the front under the 2 c-map cards is a small usb connector. the manuel only mention it is a usb slave connection.

Wath can i do with it ?
Do i need software to connect to the plotter ?

i also cannot use a c-card to transfer data, the plotter give the error message "C-card not valid"

Best regards,
Patrick