The joint VDMA and OPC Foundation Working Group “VDMA OPC UA Weighing Technology Initiative” developed an OPC UA information model for communication of scale systems. Scale systems are defined as devices within a value chain that measure the weight or mass flow of a product or Object containing several additional parameters (e.g., price, tare of packaging, etc.). Scale systems stand for a complete weight measuring device that includes one or multiple scales. The scales may fulfill different use cases within one scale system (e.g., filling and price labeling). Each scale consists of one or multiple load cells which capture the weight. It is the smallest unit regarding the components of a scale system within this Companion Specification.

The OPC UA Weighing Technology Companion Specification covers the following scale system types directly: Automatic Filling Scales, catchweigher (Automatic Price Labeling Scales, Automatic Weight Labeling Scales, checkweigher), Continuously Scales, Hopper Scales, Laboratory Scales, Piece Counting Scales, Simple Scales, Totalizing Scales and Vehicle Scales.

Other scale systems including weighing bridges may be modeled based on this Companion Specification, but probably need to be extended by certain parameters.

NOTE: The scale system class “Retail Scales” is excluded by this information model. At this time there is no relevance for an OPC UA interface and therefore there is no information modelled for representing these devices.