1. A lithography system comprising one or more lithography elements, each lithography element arranged for independent exposure of substrates according to pattern data, and each lithography element comprising a plurality of lithography subsystems, the lithography system further comprising: a control network forming a control network path between the plurality of the lithography subsystems and at least one element control unit for communication of control information; wherein the lithography system is arranged for: issuing control information to the at least one element control unit to control operation of one or more of the lithography subsystems for exposure of one or more wafers; issuing a process program to the element control unit, the process program comprising a set of predefined commands and associated parameters, each command corresponding to a predefined action or sequence of actions to be performed by one or more of the lithography subsystems, and the parameters further defining how the action or sequence of actions are to be performed, wherein the element control unit is arranged to transmit a command of the process program to a lithography subsystem to be executed by the lithography subsystem, regardless of an execution status of a preceding command transmitted to the lithography subsystem, and wherein the element control unit is configured to transmit a sequence of repeated commands to the lithography subsystem, wherein the lithography subsystem discards a command in the sequence, if the command in the sequence is not executed within a time period.