A hydraulic system (1) is provided comprising a group of at least two valves (2a, 2b, 2c) connected to a bus (8), each of said valves (2a, 2b, 2c) comprising a primary memory (9a, 9b, 9c) for storing a set of parameters of the valve (2a, 2b, 2c). The service work of such a hydraulic system should be facilitated. To this end each valve (2a, 2b, 2c) comprises a secondary memory (10a, 10b, 10c) storing said set of parameters of a different valve (2b, 2c, 2a) of said group.