There is described a packaging machine (1) for producing sealed packages (2) of a pourable food product from a strip (6) of heat-seal sheet packaging material. The packaging material (1) has a number of photocells (14), which are programmable externally as regards their setting parameters, are positioned facing the strip (6) of packaging material to detect optically detectable elements on the strip, and have setting means (26, 210, 300). The packaging machine (1) also has a control unit (16) connected to the photocells (14) and having enabling means (24) for enabling the setting means of a specific photocell (14), data downloading means (26, 240, 310) for downloading off the specific photocell (14) the setting parameters of the photocell, and data uploading means (26, 260, 330) for uploading onto the other photocells (14) setting parameters calculated as a function of the setting parameters downloaded off the specific photocell (14).