16.4 Use case 2: Automated assembly line directed by MES

Problem Statement

Imagine a plant with an automated assembly line, which is directed by an MES (Manufacturing Execution System) and operated by line/cell controllers (PLCs). The joining system is controlled by a PLC.

The MES directs the joining process of individual joints via PLCs, but the handling of results.

is limited via traditional communication channels, like fieldbus networks.

relies on propriety data channels that require different implementations depending on the manufacturer.

This use case can be applicable for the following communication setup:

Joining system with OPC UA and fieldbus interfaces.

Joining system with only OPC UA.

Pre-requisite

OPC UA interface and optionally an existing fieldbus network.

Workflow

The MES controls the flow of parts via

OPC UA

PLCs and their fieldbus interfaces (if available)

The MES/PLC sends the product/part identification (e.g. VIN), joining program and start signal via

OPC UA

Fieldbus

The joining system performs the joining operation.

The MES systems receive the (extensive) joining result via OPC UA, including the joint identification.

Outcome

The results received by the MES contain the following:

the simple result one would expect from a fieldbus interface.

the extensive result, containing optionally individual step results and/or trace data representing the whole joining process.

the product/part identification, allowing the MES to relate a set of results to specific parts and/or the individual joint.

Furthermore, the result is delivered in a standardized way, which is shared by different manufacturers.