Patent ID: 8054475

Claim:
An image forming system comprising: an image forming apparatus adapted to form an image on a printing medium; a plurality of printing-medium feeding devices removably attached to said image forming apparatus; a common first signal line connecting said image forming apparatus and each of said plurality of printing-medium feeding devices, said first signal line being adapted to transmit a command from said image forming apparatus to each of said plurality of printing-medium feeding devices; and a common second signal line connecting said image forming apparatus and each of said plurality of printing-medium feeding devices, said second signal line being adapted to transmit status information of said printing-medium feeding devices from said plurality of printing-medium feeding devices to said image forming apparatus in response to the command, wherein said image forming apparatus has a transmitting unit adapted to specify one of said plurality of printing-medium feeding devices and transmit the command via said first signal line, the specified printing-medium feeding device has a transmitting unit adapted to transmit first information via said second signal line in response to the command transmitted by said transmitting unit of said image forming apparatus, and an unspecified printing-medium feeding device has a control unit adapted to concatenate second information with the first information.