We present the first results of a comprehensive photometric O-star survey performed with a robotic twin refractor at the Universitatssternwarte Bochum located near Cerro Armazones in Chile. For three high-mass stars, Pismis 24-1, CPD − 51∘ 8946, and HD 319702, we determined the period through the Lafler-Kinman algorithm and modelled the light curves within the framework of the Roche geometry. We introduce a newly discovered eclipsing high-mass binary HD 319702 that shows well-defined eclipses favouring a detached configuration with a period of 2.0 days and an orbital inclination of 67.5∘ . Combining our photometric result with the primary spectral type O8 III(f) (T 1 = 34 000 K) we derive a temperature of T 2 = 25 200 K for the secondary component.