Abstract: A device for a secure data connection of at least one manufacturing machine (104) has an information-processing system (114), which is subdivided into individual zones (108, 110, 112) interconnected by data diodes (120) such that data originating from the machine control (118) of the manufacturing machine (104) in a data flow can be transferred to other zones (108, 110, 112) without the possibility of a data return flow. The individual zones (110, 112) are ordered hierarchically. Each individual zone has a lower level of data security than the upstream individual zone (108, 110) in relation to the data flow. Every individual zone (108, 110, 112) is formed as an independent computer in the manner of an isolated application. In addition, a manufacturing machine and a production plant includes the device for secure data connection.