The Unified Namespace – the remaining questions

Having built our Unified Namespace (UNS) on MQTT and Sparkplug B, we have the infrastructure in place to enable bidirectional communication between any node in our system. This applies to edge nodes as well as devices, and also to any connected MES or ERP system. In that sense, it should be possible to have a MES send instructions to an edge node or device to initiate an action. In return, the results could be sent back to the MES.

However, some issues prevent us from doing that. The first issue is the Sparkplug B specification showing a one-directional arrow from the Sparkplug B broker to the MES, implying that messages go from the broker to the MES, but the MES never sends anything back. Could this be a flaw? While many MES systems communicate directly with PLCs, Sparkplug B was designed to collect data from devices and send them to Scada or MES systems, not the other way around. In essence, the Unified Namespace and the enabling technology Sparkplug B are intended for collecting data to support a data-driven approach to manufacturing and manufacturing improvement.