A control apparatus (100) for driving a luminaire with, a signal input (101), a signal output (102), and a signal processing apparatus (104), in which the signal input (101) is configured to receive a serial input signal (21) of the length N, the signal processing apparatus (104) is configured to shorten the input signal (21) by a control signal (23) of the length n, the signal output (101) is configured to output an output signal (22), which comprises the input signal (21) shortened by the control signal (23), and the signal processing apparatus (104) comprises a UART (11) and a switching element (10), the UART (11) being configured to switch the switching element (10) as the control signal (23) is input, with the result that the switching element (10) shortens the input signal (21) by the control signal (23).