The new EL3773 power monitoring terminal for the Beckhoff EtherCAT I/O system is designed to monitor the condition of a three-phase AC or a DC mains network. It collects instantaneous values of power and voltage at an extremely fast sampling rate of up to 10,000 samples/sec and makes them available to the higher-level PC controller for calculation or analysis. The input channels are transferred via oversampling; this results in the acquisition of actual values with a significantly higher resolution in terms of time than the communication cycle time. The EtherCAT distributed clocks method is used as the basis for the highly precise acquisition of measured values in the EtherCAT Terminal system. These distributed clocks synchronize the EtherCAT devices with very high precision, independently of the PLC cycle. The EtherCAT Terminal measures voltage and current via three channels in each case. The six channels are measured simultaneously based on the EtherCAT oversampling principle with a temporal resolution of up to 100 μs and passed on to the controller. The maximum sampling frequency for each channel is 10 kHz.