A method of electrical communication between a slave node of an I2C communication bus positioned on a replaceable supply item installed in an image forming device and a controller of the image forming device as a master node of the I2C communication bus , comprising: receiving a first write command by the slave node on the replaceable supply item from the controller of the image forming device ; comparing by the slave node on the replaceable supply item a value of a transmission cycle bit (tc n ) contained in a header of the first write command with a value of a transmission cycle bit (tc n-1 ) contained in a header of a second write command received by the slave node on the replaceable supply item from the controller of the image forming device previous to the first write command; and if the value of the transmission cycle bit (tc n ) contained in the header of the first write command is equal to the value of the transmission cycle bit (tc n-1 ) contained in the header of the second write command, comparing by the slave node on the replaceable supply item a value of a command ID (Command n ) of the first write command with a value of a command ID (Command n-1 ) of the second write command; and if the value of the command ID (Command n ) of the first write command is equal to the value of the command ID (Command n-1 ) of the second write command, sending (409 by the slave node on the replaceable supply item to the controller of the image forming device a response to the second write command without executing the first write command. receiving a first write command by the slave node on the replaceable supply item from the controller of the image forming device ; comparing by the slave node on the replaceable supply item a value of a transmission cycle bit (tc n ) contained in a header of the first write command with a value of a transmission cycle bit (tc n-1 ) contained in a header of a second write command received by the slave node on the replaceable supply item from the controller of the image forming device previous to the first write command; and if the value of the transmission cycle bit (tc n ) contained in the header of the first write command is equal to the value of the transmission cycle bit (tc n-1 ) contained in the header of the second write command, comparing by the slave node on the replaceable supply item a value of a command ID (Command n ) of the first write command with a value of a command ID (Command n-1 ) of the second write command; and if the value of the command ID (Command n ) of the first write command is equal to the value of the command ID (Command n-1 ) of the second write command, sending (409 by the slave node on the replaceable supply item to the controller of the image forming device a response to the second write command without executing the first write command. comparing by the slave node on the replaceable supply item a value of a command ID (Command n ) of the first write command with a value of a command ID (Command n-1 ) of the second write command; and if the value of the command ID (Command n ) of the first write command is equal to the value of the command ID (Command n-1 ) of the second write command, sending (409 by the slave node on the replaceable supply item to the controller of the image forming device a response to the second write command without executing the first write command. <EOS>