A packaging machine includes a conveying device for advancing a packaging material web at least to a tube forming station at which the web is formed into a tube and for advancing the tube to a tube forming and sealing device to form and longitudinally seal the tube, a tensioning device to control tension of the web and/or of the tube and a control unit to control operation of the packaging machine. The tensioning device has at least one tensioning assembly having at least first and second drive rollers, a first drive motor connected to the first drive roller to rotate the first drive roller and a second drive motor connected to the second drive roller to rotate the second drive roller. The control unit controls the first and second drive motors such that a free loop of the web expands and/or advances between the first and second drive rollers.