The challenge: supervise a plant room without the cost of a SCADA
The client, operator of a temperature-controlled logistics centre in the Henares Corridor (Madrid), needed to unify the supervision of its entire plant room: two chillers, the chilled- and hot-water circulation pumps, domestic hot water (DHW) production, dock ventilation and a monitored fire-fighting pressure set. Each piece of equipment came with its own factory control logic, but the operator had no overall picture: to find out why a cold room's temperature was rising, a technician had to physically walk the plant room reading local displays.
The initial quote they had received was for a commercial SCADA with per-tag and per-client licensing, plus a dedicated server. For an installation of this size, the licensing cost and the upkeep of that server were not justified. They contacted us looking for an industrial automation company in Madrid that could give them the same visibility with a lighter, cheaper-to-maintain architecture.
Why we chose Codesys WebVisu
After surveying the installation, we proposed dropping the SCADA and solving supervision with WebVisu, the visualisation feature built into the Codesys runtime. The PLC itself acts as a web server and serves the HMI screens directly to any browser on the network, with no additional client software and no per-tag licensing.
For a plant room with a bounded number of equipment items and concurrent operators, WebVisu was a perfect fit: the operator needed to see states, trends and alarms and to adjust setpoints — not to build a distributed SCADA architecture with a massive historian or dozens of simultaneous client stations. The decision followed exactly the criteria we describe in our guide on WebVisu versus traditional SCADA.
Solution architecture
Field control was solved with two Wago PFC200 controllers programmed in Codesys, distributed by proximity to the equipment to minimise field wiring. On top of them we mounted the Wago 750 I/O system for the digital and analogue inputs and outputs, and we integrated the existing equipment over fieldbus rather than rewiring it:
- Chillers and DHW set: integrated via Modbus TCP, reading setpoints, run states, alarms and consumption directly from their factory controllers.
- Pumps and fans with drives: control and feedback of the variable frequency drives over Modbus, with start/stop and speed setpoint managed from the PLC.
- Plant sensors: PT100 temperature probes, pressure switches and flow meters wired directly to the Wago I/O modules.
- Upper integration layer: an OPC-UA server embedded in the PFC200 makes the data available to the client's management system, without opening up the WebVisu to external systems.
The two PFC200s communicate with each other over the plant network and share a common process image, so the WebVisu of either one shows the complete state of the plant room regardless of which controller governs each piece of equipment.
The WebVisu: a plant room in the browser
We designed the visualisation screens in the Codesys graphical editor, binding each element directly to the program variables. The result is an HMI accessible from any browser on the network by simply opening the controller's URL, with nothing installed on the client:
- General overview: a process schematic of the whole plant room — chillers, headers, pumps, DHW and ventilation — with run states, temperatures and flow rates in real time. A valve or pump changes colour according to the state of its associated boolean variable.
- Per-subsystem detail screens: each equipment item has its own view with editable setpoints, manual/automatic modes and alarm diagnostics.
- Trend charts: evolution of supply/return temperatures and consumption, useful for spotting drifts before they cause an incident.
- Alarm manager: a list with timestamp, acknowledgement and priority, replacing the physical walk through the plant room the operator used to do.
On-site, the WebVisu is consulted from an industrial tablet fixed next to the plant room and from the maintenance PCs. Because the interface is responsive, the same project displays correctly on a tablet, laptop or smartphone screen with no extra development.
Secure remote access for maintenance
So that the client's maintenance team — and our own support — could check the installation without travelling, we did not expose the WebVisu to the internet. Instead we set up secure remote access over VPN to the plant network, so the WebVisu is only reachable once the encrypted tunnel is established. This is the same approach we apply in our remote connection projects and detail in the article on the importance of remote support for incidents, aligned with OT cybersecurity best practice: industrial network segmentation, no direct publication of the PLC's web server, and authenticated access.
Commissioning and on-site validation
The installation was carried out without stopping the centre's operations, integrating the equipment one by one. The validation process included:
- Modbus integration validation: checking, equipment by equipment, that each reading and each command over the bus matched the asset's real behaviour.
- WebVisu verification: walking through every screen on tablet, laptop and smartphone, validating refresh, setpoints, manual/automatic modes and alarm acknowledgement.
- Real alarm tests: controlled triggering of faults (a pump trip, a temperature drift) to validate the alarm → notification → log chain.
- Supervised operation: accompanying the maintenance team during the first days to fine-tune setpoints and thresholds according to the plant room's real behaviour.
Results
- Full visibility of the plant room from a single web interface, versus the physical walk the previous system required.
- Licensing cost eliminated: because the HMI is served from the Codesys runtime itself, there are no per-tag or per-client SCADA licences, nor a dedicated server to maintain.
- Faster incident diagnosis: the alarm manager with history makes it possible to locate the source of a fault from the browser, without going to the plant room.
- Secure remote maintenance: the client's team and our support access the WebVisu over VPN, reducing site visits for minor incidents.
- Data ready for the future: the embedded OPC-UA server leaves the door open to integrating the plant room into an energy management system or a wider plant dashboard later on.
What made this project different?
The key was not any exotic technology, but sizing the solution to the real problem. For a plant room with a bounded number of equipment items and operators, a commercial SCADA would have been oversized and expensive to maintain. WebVisu on Wago PLCs programmed in Codesys delivered exactly the supervision the client needed, with a lightweight architecture, no recurring licences and all the data available via OPC-UA for when they want to take the next step.
If you run an installation in the Madrid region and are wondering whether you need a full SCADA or a well-designed web supervision is enough, tell us about your case. We assess the most suitable architecture and the project scope with no obligation.