exists operation s 550 y the bluetooth master inserts the target slave device information stored therein into the received data to generate l2cap data and transmits the generated l2cap data only to the target slave device operation s 570 here the presence of the target slave device indicates that the bluetooth master has transmitted the same data as the received data once or more i e that the bluetooth master has received response data from a slave device corresponding to the transmitted data and has stored slave device information for example an ip address a port number and a key value of the slave device inserting the target slave device information into the data even though the key value is inserted into the data is intended to cope with the sudden possibility of data loss and to prevent transmission failure caused by a key value being lost between bluetooth devices due to communication errors in the exemplary embodiment of fig9 operations s 510 s 520 and s 530 have been described as being performed before the bluetooth master receives data from the access point operation s 540 in another exemplary embodiment however the operations may be performed after the bluetooth master receives data from the access point operation s 540 and therefore the present general inventive concept is not limited thereto fig1 is a flowchart illustrating a method of storing slave device information according to an exemplary embodiment of the present general inventive concept referring to fig1 a bluetooth master receives from any slave device response data to data that the bluetooth.