Data Acquisition Systems (DAS) are the basis for building monitoring tools that enable the supervision of local and remote systems. DASs are complex systems. It is difficult for developers to compare proprietary generic DAS products and/or standards, and the design of a specific DAS is costly. In this paper we propose a conceptual model of a generic DAS. This model gives DAS developers an abstraction of DASs; it enables them to compare existing products and standards; and it provides the DAS developers that aim to develop a specific DAS with a starting point for the design of a specific DAS. We have found that a conceptual model of a generic system has many advantages. We propose patterns and techniques that are useful for the development of conceptual models of generic systems.