The invention relates to a method for operating a processing device (2) that comprises a control unit (4) and at least one field device (8, 10, 12) connected to said control unit (4) for the purpose of exchanging data via a data exchange connection (6), in which a field device (10) to be exchanged is replaced by another field device (12) to be inserted, and which comprises the steps of: generating an exchange signal (AS) using an exchange signal generator (14), and transmitting said exchange signal (AS) to the control unit (4). The invention also relates to a corresponding processing device and a control unit, field device, and exchange signal generator, as well as a computer program.