Method for operating a system of modular structure, in particular a process automation system

A method for operating a system of modular structure, which is extendable during operation by adding modules consuming electrical energy, comprising:

• providing a power supply for the system, wherein the power supply supplies the modules of the system consuming electrical energy with electrical energy;
• generating a signal for
• a remaining residual power for a further module to be added, wherein the signal is generated before the further module consuming electrical energy is added to the system, or
• a level of power, which the power supply supplies currently to already added modules, or
• identifying or deriving whether the further module to be added can be added without overloading the power supply;
• and
• displaying the signal;
• wherein a computation and control facility assigned to the system determines or takes from a storage unit a maximum number of addable modules respectively for different classes of modules of different power consumption values, the maximum number of addable modules being the number of addable modules which can be added without a predefined overload power limit value being reached or exceeded, and
• a class-dependent, maximum number is determined from upper power consumption limit values assigned to each class, which respectively form an upper limit for all addable modules of each corresponding class, and from a current value of a residual power of the power supply provided to the already added modules.