ZenonMetricsExporter ELT is a proof of concept MVP to extract live internal data from an SIMATIC S7 PLC and a B&R system without it's source code.
I think a diagram speaks a 1000 words to explain the whole set up. Its basically a normal ETL pipline (Extract, Transform, Load) that loads as much internal data from a system to do some easy explorative analysis.
| Component | Responsibillity | Detail |
|---|---|---|
| S7 PLC | Controls an Kran suppliying a Wood gasifier with fuel. | Contains live KPI'se e.g. Wood usage |
| B&R PLC | Controls Wood gasifier plant / produce electricity | KPI data maybe useful for maintence planning |
| CloudMetrics Relay | Transform types, varibale names, and store it | Received data exporters "service" |
| Kapacitor | enforce monitoring rules | Alert via telegram if expected data is missing |
| Chronograf UI | Query data, Display graphs and create dashboards | Current interface to Influxdb |
| InfluxDb | Store , Query, intervals aggregation, trash old metrics | InfluxDB an time series database for lage volumes of data |
Reverse engineer, the PLC controllers, was the most challenging and rewarding part of this project. It fascinated me to learn how industrial automation components work. It is a simple low-level computer with a network interface that exposes its variables using a memory address register and fix sized data types.
Perhaps WebSockets was not the best choice of protocol. My initial thought was it might become beneficial to keep a bi-directional connection between the exporter server. The need to keep message sizes small has created an unnecessary overhead of complexity, especially since an HTTP Post would have been just fine.