From RFID to MES/ERP and into the Cloud
Author: Stefan Hoppe, President OPC Europe (TwinCAT Product Manager at Beckhoff
OPC? You must mean that old standardization technology enabling data exchange between visualization and PLC controller. And interoperability is basically just a marketing buzzword, anyway. The same as "openness" and "modularity", which everyone offers. If you mentally agreed with this introduction, you’re "old school", according to which the automation pyramid consists of very clearly separated layers in which the field devices, sensors and actuators are connected to a controller via electrical signals, RS232 or USB. The controller processes these signals into data and relays them onwards to higher control levels, after which everything ends up in the MES-ERP level via web services at some point or another.
This model is fundamentally based on the assumption that, in terms of communication, an RFID reader or the PLC are “dumb“, and always merely respond to requests "from above". The higher level is always the client and initiates data requests – the lower layer is always the server and courteously responds.
Just a dream?
The dream would be that all devices and services could communicate with each other independently – regardless of the given manufacturer, operating system, hierarchy and topology. The functionality offered by devices should be readable – but not for everyone – meaning security must be present directly in the device along with authentication and encryption. And, in the event of the failure of a data link, data should not be lost, but rather automatically buffered for a certain interval of time.
In reality, all these wishes have already come true: interoperability based on OPC Unified Architecture is the key, as long as rigorous real-time requirements are not involved. HARTING recognized the potential of OPC UA early on and integrated it into its RFID reader.
So there’s no question: OPC UA provides seamless connectivity, from the most compact sensors through to the Cloud. Much more important, however: a UA client in the RFID reader enables the latter to independently initiate communication and relay data directly to the MES system without a PLC. Which kind of disrupts the pyramid, don’t you think? Most definitely – with OPC UA, every device can exchange information with any other service or device, regardless of whether it runs at the field level or in the Cloud. As a result, intelligent solutions – directly from HARTING RFID reader all the way to SAP – have become implementable reality.