The present disclosure relates to a system and method for determining or monitoring a process variable having a higher-level unit and a plurality of field devices. The field devices generate data and are connected to one another for communication, and the higher-level unit and the field devices are nodes corresponding to a distributed ledger or blockchain technology comprising transaction creation units. Each field device is assigned a transaction creation unit for creating transactions. A created transaction contains data from the field devices assigned to the transaction creation units. A block creation unit processes a created transaction to form a data block. Validation units check the data block and/or transactions for validity. The data block is valid if at least one predefined number of validation units validates the data block, wherein each node is assigned one of the validation units. The valid data block is stored in a distributed database.