There is provided a sensor system for use in a high voltage direct current network. The sensor system comprises a plurality of sensor devices, each sensor device configured to obtain a respective sensor measurement, wherein the plurality of sensor devices are configured to generate a serial data unit for transmission to a recipient system, the serial data unit configured to include the plurality of sensor measurements (S1, S2, Sn), the serial data unit further configured to include a plurality of validity indicators (FCS1, FCS2, FCSn), each validity indicator (FCS1, FCS2, FCSn) configured to provide an individual validity status of a respective one of the plurality of sensor measurements (S1, S2, Sn).