PLC to MES Interconnection for Industry 4.0Real-time machine connectivity over OPC-UA

Many Italian manufacturers are asking the same question this year: how do we connect our PLC machines to our software so they qualify for Industry 4.0 incentives?

The reason is the new iperammortamento introduced by the 2026 Budget Law (Law 199/2025). It covers new capital goods bought between 1 January 2026 and 30 September 2028, and like the earlier Industry 4.0 schemes, it rests on one technical test: the machine must be interconnected with the factory's management systems. A machine that only has a CNC or PLC, but isn't connected, does not meet the requirement.

Interconnection isn't only a tax requirement, either. Once machines talk to the MES, you get real production times, piece counts and alarms without anyone typing them in.

Annex IV of the 2026 Budget Law lists the physical assets that can benefit. For machines controlled by CNC or PLC, all five of these characteristics are mandatory:

#	Mandatory characteristic	What it means on the shop floor
1	Control by CNC and/or PLC	The machine is run by a programmable controller
2	Interconnection with factory IT systems, with remote loading of instructions and/or part programs	The MES sends work orders and instructions to the machine
3	Automated integration with the factory logistics system, the supply network or other machines	Machine data flows into planning and other systems without manual steps
4	Simple, intuitive human-machine interfaces	Operators can read and control the machine easily
5	Compliance with current health, safety and hygiene standards	The machine meets workplace safety rules

The machine must also have at least two of these three:

• Remote maintenance, remote diagnostics and/or remote control
• Continuous monitoring of working conditions and process parameters through sensors, adapting to process drift
• Integration with a model or simulation of its own behaviour (a cyber-physical system or digital twin)

Annex V covers intangible assets. It explicitly lists MES systems among production management software and Industrial Internet of Things platforms among software that shares data. The software that connects the machines can therefore be an eligible investment in its own right.

In our custom MES project for SEA, we built our own edge router that sits between the shop floor and the MES.

• One router, many machines. The router manages the OPC-UA connection with each machine's PLC. Machines are connected dynamically, so adding a machine doesn't mean writing a new integration.
• Data in both directions. The MES loads work orders and production instructions onto the machines remotely. The machines send back their status, process parameters, piece counts and alarms in real time.
• Every exchange is logged. Each message between the MES and the machine is recorded with a timestamp, so there is a complete history of what each machine received and reported.

Today every machine on the client's floor is connected, and the MES reads machine data as it happens. Our customers in Italy use the same setup to meet the interconnection requirement for Industry 4.0.

OPC-UA (Open Platform Communications Unified Architecture, standardised as IEC 62541) is the most widely supported protocol for this job:

• Vendor-neutral. Siemens, Beckhoff, B&R, Omron and most other PLC makers support it, so one approach covers a mixed fleet of machines.
• Structured data. OPC-UA exposes a machine's data as a typed information model, not just raw registers, which makes mapping to MES concepts like work orders, operations and counters much cleaner.
• Secure by design. It supports encryption, certificates and user authentication, which matters when the production network connects to business systems.
• Read and write. The same connection that reads temperature and piece counts can write a work order or a recipe to the machine, which is exactly what remote loading of instructions requires.

To claim the incentive, the company needs a sworn technical report (perizia tecnica asseverata) from an engineer or expert. The report confirms the asset's technical characteristics and its interconnection.

A connected MES makes that report much easier to write, because the evidence is already there:

• the list of connected machines and their network identity
• logs of work orders sent from the MES to each machine
• the production data, alarms and parameters each machine sent back
• screenshots of the MES showing live machine status

We provide this technical documentation to our customers and their experts. The eligibility decision itself always rests with the expert and the company's tax advisor.

1. List your machines. For each one, note the PLC brand and model and whether it already has an OPC-UA server or other open interface.
2. Define the data. Decide what the MES should send (work orders, recipes, part programs) and what it should read (status, counters, parameters, alarms).
3. Connect a pilot machine. Connect one machine end to end, from PLC to router to MES, and check the data with the operators who run it.
4. Roll out and document. Connect the remaining machines and keep the logs and documentation the technical expert will need.

Machine interconnection is where Industry 4.0 stops being a slogan and becomes real data in your MES. If you're planning new machines under the 2026 iperammortamento, or want your existing MES to read and control your PLCs in real time, read our MES case study or get in touch to talk about your machines.

This article is general information and not tax advice. Incentive rules can change, so always check the current legislation and implementing decrees with your tax advisor.