Image supply device and control method thereof

The invention provides a recording device, image supply device, recording system, and control method thereof. When the function of a printer has been changed, the printer notifies a DSC of a change in printer function using a capabilityChanged tag. If the DSC does not return any inquiry about the capabilityChanged tag, the printer determines that the DSC has no function that supports the capabilityChanged tag. The printer executes disconnection and re-connection of USB to execute a communication procedure with the DSC from the beginning, thereby notifying the DSC of the latest capability information in the printer.