Canon C2050 Service Handbook page 249

<INT-FACE>
Setting Conditions (when an external controller is connected)
B-CLR
When Releasing the Copy Data Controller-A1 After Installation
Settings 0: Not connected
1: Connected
Use If you want to temporarily release the Copy Data Controller-A1 at time of
servicing work, set '0'.
Reference When a Copy Data Controller-A1 is installed, the setting will automatically
be '1'; if the controller is release without setting '0' to it, the machine will
indicate error code E717.
SERVICE MODE
COPIER/PRINTER>OPTION
S-107