Method for Payment-Based Execution of a Function of a Field Device to be Performed, Corresponding Field Device and Service Unit

A method for payment-based execution of a function of a field device to be performed, wherein the field device has an identifier and is connected to a process control system via a first communication channel, the process control system is connected to a service unit via a second communication channel, the field device and the service unit each have at least one time-counting device, and the time-counting devices are synchronized with one another and each provide a time value of the field device and a time value of the service unit, the method comprising:

• a selection step, wherein the process control system selects the function to be performed on the field device from a selection list of executable functions of the field device available to the process control system, and the process control system communicates the selected function to the service unit;
• a payment step, wherein a payment amount specified for the function to be performed is paid by a payment service and the payment of the payment amount is confirmed by the payment service to the service unit by transmission of confirmation information;
• a request step, wherein the service unit determines a derived time value of the service unit, which is dependent on the current time value of the service unit, and an enable code, which is dependent on the function to be performed, and transmits the enable code to the process control system;
• a forwarding step, wherein the process control system forwards the enable code to the field device;
• a checking step, wherein the field device determines a derived time value of the field device which is dependent on the current time value of the field device, and checks the enable code using the derived time value of the field device to determine whether the enable code is generated by the service unit, and the field device determines the function to be performed from the enable code;
• and
• an execution step, wherein the field device executes an executable code corresponding to the function to be performed in the event that the enable code received by the field device is verified as being generated by the service unit.