A practical engineering guide to non-invasive data acquisition in brownfield environments.
The belief that a unified production monitoring system requires a modern, uniform machine park is one of the most common myths in manufacturing. Whether a machine has the latest Siemens S7-1500 controller, an older S7-300 from the 1990s, a proprietary Fanuc/Heidenhain CNC controller, or is a fully analogue relay-based machine, there is a proven, non-invasive path to digitalising it. Using industrial protocols (OPC UA, Modbus TCP, S7Comm), external Remote I/O modules, non-invasive current transformers and hardware gateways with OT/IT network separation, you can connect 100% of a mixed machine park to one consistent dashboard within a few working days – or longer, depending on the size and complexity of the machine park.
In almost every factory that has been running for more than a few years, the reality on the shop floor looks similar: it is a so-called brownfield environment. Next to a modern 5-axis CNC machining centre stands a 25-year-old hydraulic injection moulding machine, further on a packing line with a Siemens S7-300 controller, and at the end a mechanical press whose entire automation is based on contactors, relays and physical push buttons.
When management hears about digitalisation and monitoring systems, the first objection from maintenance and automation teams is: “It won’t work here. Our machines are too old, and integrating all these different controllers will cost millions and risk stopping the line or voiding the warranty.”
That is a widespread myth. Modern production process data acquisition makes it possible to connect any industrial machine completely non-invasively – without stopping production, without modifying PLC code and without any risk of disrupting technological processes.
1. Three levels of data acquisition: from pure software to physical measurement
In industrial engineering there is no “one size fits all” approach. Depending on the machine’s year of manufacture and equipment, data is collected at one of three levels.
Level 1: Modern machines with digital PLCs (software-only)
Modern controllers (Siemens S7-1200/1500, Beckhoff, B&R, newer Omron and Schneider series) have built-in Ethernet ports and native support for open standards:
- OPC UA (IEC 62541): A secure, encrypted, object-oriented protocol. The gateway reads process variables directly from the OPC UA server integrated in the PLC.
- Modbus TCP / EtherNet/IP / MQTT: Reading memory registers (holding registers, inputs) directly over the local network.
- Level of invasiveness: zero. All it takes is plugging an Ethernet cable from the controller into the iPLAS Gateway and exposing the DB blocks in read-only mode.
Level 2: Machines with older-generation controllers (legacy PLCs)
Many factories are dominated by reliable units that have been running for decades, such as Siemens Simatic S7-300/400, or machines with RS-485 / Profibus DP serial ports:
- S7 Communication protocol (S7Comm): Lets the gateway read the controller’s marker memory (M) and data blocks (DB) directly from an S7-300, without uploading any changes to the program in Step 7 / TIA Portal.
- Profibus/MPI to Ethernet adapters: If the controller has only a DB9 serial port (no RJ45 socket), bus adapters (e.g. NetLink/IBH Link) are used to convert the signal to Ethernet.
- CNC protocols (Fanuc FOCAS, Heidenhain DNC): Reading spindle parameters, the current tool number, error codes and feed rate directly from the machine controller.
Level 3: Analogue, relay-based and vintage machines (hardware retrofit)
What do you do with a 30-year-old hydraulic press, guillotine or furnace whose automation relies solely on contactors and fuses? We do not replace the control cabinet. We use non-invasive external sensors:
- Non-invasive current transformers (CT clamps): A split-core measuring coil is clamped around the supply cable of the machine’s main motor. Measuring current (A) in real time immediately reveals the machine state: 0 A = off, 3–5 A = idling (hidden downtime), 18 A = productive cycle. Installation takes 15 minutes, with no cable cutting and no power shutdown.
- Signals from Andon lights and auxiliary contacts: The 24 V DC voltage from signal towers (green/red light) is fed into the inputs of a miniature Remote I/O module (Modbus TCP), which turns voltage states into digital data frames.
- External cycle sensors: An additional inductive or optical sensor on the part ejector counts pieces and measures cycle time 100% independently of the machine.
Because physical parameters (current, vibration, temperature) are captured, this data also becomes the foundation for predictive maintenance and fewer breakdowns.
2. Security and network architecture: separating OT from IT
The main concern of automation engineers and IT departments is that connecting machines to a higher-level network will open the door to cyber threats. Professional iPLAS deployments use an architecture based on the IEC 62443 standard / Purdue model:
- Dual-NIC hardware separation: The industrial gateway has two physically separated network cards. One connects only to the machine subnet (OT, no routing to the internet), the other to the plant network (IT) or an LTE modem.
- Read-only communication only: The gateway polls machines passively. It has no permission to upload code or control motion remotely, which rules out the risk of a process accident.
- Local data buffer (fail-safe): If the plant network fails, the gateway stores data in local industrial memory and sends it automatically once the connection is restored.
3. A practical implementation example: a battery systems manufacturer
An example of successfully integrating diverse production lines and utilities is the deployment at a leading battery systems manufacturer. iPLAS integrated data from automated assembly lines and utility supply systems there, giving management precise, real-time insight into performance and process parameters.
4. An engineering integration checklist in 4 steps
- Signal matrix. List the machines, controller types and the minimum set of variables: operating state (running/stopped/alarm), cycle counter, cycle time.
- Connector selection. Choose the path: a digital protocol (OPC UA/S7Comm) for machines with PLCs, or a Remote I/O module + CT clamp for older machines.
- Data normalisation. Map the varied signals from different machine brands to one unified variable model in the iPLAS platform.
- Dashboard launch. Visualise OEE, downtime and KPIs on shop-floor TV screens and in the reporting portal.
Summary
You don’t have to replace your machine park or invest hundreds of thousands in modernising control cabinets to get reliable OEE figures, eliminate unplanned downtime and keep precise control of energy costs. Thanks to hardware gateways, passive read-only protocols and non-invasive measuring transformers, a 30-year-old hydraulic press delivers production facts just as precise as a brand-new 5-axis CNC machining centre.
Next step: get a free consultation on connecting your machine park
Do you have machines on the shop floor that nobody has managed to connect to a system yet? Or are you worried that IT will block the project for network security reasons?
- Analysis of your machines: Send us a list of 2–3 machines (year of manufacture, manufacturer, PLC controller model or a note that there is no electronics).
- Choosing a non-invasive method: Within 24 hours, free of charge, we will prepare a preliminary signal matrix and show you the fastest way to connect them (software-only vs retrofit).
- A ready diagram for IT: We will prepare a network architecture diagram compliant with IEC 62443 (Dual-NIC), ready for approval by your network / IT security administrator.
➔ Submit your machines for a free integration analysis
Sources and technical standards
- OPC Foundation: OPC Unified Architecture specification (IEC 62541) for secure interoperability in automation.
- ISA / IEC 62443: international cybersecurity standards for industrial automation and control systems (IACS) and the Purdue model.
- Modbus-IDA / Schneider Electric: Modbus Application Protocol Specification V1.1b3.
- Siemens AG Technical Documentation: SIMATIC S7 Communication Protocols & Industrial Ethernet Interface Manuals.
