1. A light control communication system comprising:a first conversion unit configured to convert an input signal in conformity with a first protocol used for controlling a lighting device into a communication signal in conformity with a second protocol;
a controller-side communication unit configured to transmit the communication signal;
a device-side communication unit configured to receive the communication signal from the controller-side communication unit; and
a second conversion unit configured to convert the communication signal received by the device-side communication unit into a control signal in conformity with the first protocol, wherein
each of the input signal and the control signal includes a first number of channels,
the first number of channels include a second number of predetermined channels including data for controlling the lighting device, the second number being smaller than the first number,
the first conversion unit extracts only data included in the second number of predetermined channels from the first number of channels in the input signal as data included in the communication signal, and
the second conversion unit generates the control signal by adding predetermined data to the data included in the communication signal to fill the first number of channels.