A modular energy system that can include a header module removably couplable to one or more energy modules. The one or more energy modules collectively comprise multiple ports to which a surgical instrument is connectable and are each configured to drive a plurality of energy modalities for the surgical instrument. The header module can comprise a display screen configured to display a user interface. The header module is connectable to a footswitch such that the header module can receive a control signal from the footswitch and can send a control signal to the footswitch. The header module can further comprise configured to assign the footswitch to a particular port and, based on user input received via the user interface, reassign the footswitch to another of the ports.