A method for verifying the functionality of a supervisory control and data acquisition (SCADA) system, the SCADA system comprising a SCADA device, an intelligent electronic device (IED) and a communication link therebetween, wherein the IED measures a physical process and stores digital data representative of the measurement in a memory area for transmission via the communication link to the SCADA device, the method comprising the steps of:
- a) communicating a verification enable command from the SCADA device to the IED via the communication link such that a verification mode is enabled in said IED;
- b) communicating simulated digital data representative of measurement data from one of the SCADA device and a local input device to the IED for storage in said IED;
- c) transmitting said simulated digital data back from the IED to one of the SCADA device and a local input device in place of actual digital data representative of the measurement.