A control device comprising: a housing including a first surface and a second surface facing away from the first surface; an input device exposed through a portion of the first surface; a communication circuit disposed between the first surface and the second surface and capable of communication with an external device; a connection circuit exposed through a portion of at least one of the first surface and the second surface and configured to be electrically connected with another control device; a processor disposed between the first surface and the second surface and operatively connected with the input device, the communication circuit, and the connection circuit; and a memory disposed between the first surface and the second surface and electrically connected with the processor, wherein the memory stores one or more instructions that, when executed, cause the processor to: when the control device is not connected with the another control device through the connection circuit, transmit a message associated with a request for execution of a first function to the external device through the communication circuit when receiving an input signal based on the input device; and when the control device is connected with the another control device through the connection circuit, transmit a message associated with a request for execution of a second function to the external device through the communication circuit when receiving a user input associated with execution of a specified function, wherein the memory additionally stores instructions that, when executed, cause the processor to: when receiving, from the external device, an instruction to change at least one of the first function and the second function, update message information that defines the first function or the second function requested from the external device. a housing including a first surface and a second surface facing away from the first surface; an input device exposed through a portion of the first surface; a communication circuit disposed between the first surface and the second surface and capable of communication with an external device; a connection circuit exposed through a portion of at least one of the first surface and the second surface and configured to be electrically connected with another control device; a processor disposed between the first surface and the second surface and operatively connected with the input device, the communication circuit, and the connection circuit; and a memory disposed between the first surface and the second surface and electrically connected with the processor, wherein the memory stores one or more instructions that, when executed, cause the processor to: when the control device is not connected with the another control device through the connection circuit, transmit a message associated with a request for execution of a first function to the external device through the communication circuit when receiving an input signal based on the input device; and when the control device is connected with the another control device through the connection circuit, transmit a message associated with a request for execution of a second function to the external device through the communication circuit when receiving a user input associated with execution of a specified function, when the control device is not connected with the another control device through the connection circuit, transmit a message associated with a request for execution of a first function to the external device through the communication circuit when receiving an input signal based on the input device; and when the control device is connected with the another control device through the connection circuit, transmit a message associated with a request for execution of a second function to the external device through the communication circuit when receiving a user input associated with execution of a specified function, wherein the memory additionally stores instructions that, when executed, cause the processor to: when receiving, from the external device, an instruction to change at least one of the first function and the second function, update message information that defines the first function or the second function requested from the external device.