One of the automation ecosystems we work with: how a Siemens system starts from a small panel and grows into a complete installation with SCADA, remote stations and a link to the office, without changing tools or rewriting everything from scratch.
Every installation is split into layers. At the bottom are the sensors and loads, above them the PLCs that make decisions, then the screens and SCADA that display and record, and at the top management and the cloud. Siemens has a product for each layer, and they all talk to each other without converters.
The PLCs, I/O modules, screens and inverters connect in a PROFINET ring. If a cable is cut, the network re-forms itself from the other side. Above the ring sits the SCADA, behind a firewall, and from there operators watch from a browser or tablet. Older PROFIBUS equipment is kept through a gateway, and remote stations connect over 4G.
PROFINET accepts all forms on the same network. A line for cheap wiring inside a panel, a star with a switch for many points, a ring where downtime is costly.
The same cable carries I/O, screens, inverters, diagnostics, engineer access and the PLC web server. There is no need for a separate network for each job.
An existing panel with an S7-300 and PROFIBUS is not thrown away. It connects through a gateway and is replaced step by step, when the budget allows.
The network is designed around where the panels are, not around the limits of the PLC. All the forms below are PROFINET and can be combined in the same project. A line inside one panel, a ring between panels and a star in the control room can coexist.
The great value of SIMATIC is that each step builds on the previous one. The program, the tags and the screens carry over to the next size inside the same TIA Portal. The customer pays today only for what is needed today.
An S7-1200 with its built-in I/O and a basic touch screen. Ideal for a pumping station, a small machine, heating.
S7-1200 · Unified Basic PanelModules next to the PLC and distributed ET 200SP I/O in other panels, over PROFINET. Less wiring, easy to add channels later.
Signal modules · ET 200SP · analog 4-20 mA / PT100Move to an S7-1500 when the logic grows or when you need speed, safety (F-CPU) or a dual PLC. The LAD program carries over, it is not rewritten.
S7-1500 · S7-1500F · S7-1500 R/HOne WinCC Unified PC station gathers many PLCs, keeps history and alarms, and opens from any browser with no client installation.
WinCC Unified PC · web clients · history in SQLDistant points over 4G and VPN, notifications, a link to ERP or the cloud through OPC UA and MQTT, analysis of energy and faults.
SCALANCE M · telecontrol CP · Industrial Edge · Insights Hub| Family | What it is for | Expansion | Characteristic |
|---|---|---|---|
| S7-1200 | Small and medium machines, pumping stations, buildings | up to 8 modules + 3 CM (large CPUs) | Economical, built-in I/O and web server |
| S7-1500 | Production plants, many signals, fast logic | up to 32 slots on the rail | Display on the CPU, Motion, OPC UA server |
| S7-1500 R/H | Water, energy, anything that must not stop | 2 CPUs in redundancy | If one PLC fails, the other carries on |
| ET 200SP | Distributed I/O in other panels | up to 64 modules per head | Slim, module change without shutdown |
| F-CPU / PROFIsafe | Emergency stops, doors, safety light curtains | on the same network | Safety logic in the same PLC and cable |
The channels on the PLC itself run out quickly. With distributed I/O (ET 200SP in other panels, over PROFINET) the limit is no longer the slots on the rail but the CPU's address range, which is much larger. So the same PLC grows from tens to thousands of signals by adding stations, without changing the program at its base.
Logarithmic scale. The grey bars are local channels only, the green ones with remote I/O. The upper limits are theoretical (address range). In practice large projects run from a few hundred to a few thousand signals, with plenty of room for future expansion.
| Solution | Remote I/O stations | Input / output range | Analog (indicative) |
|---|---|---|---|
| S7-1200 | up to 16 PROFINET devices | 1 KB / 1 KB | Up to 512 channels (2 bytes each) |
| S7-1500 | 128 to 512, depending on the CPU | 32 KB / 32 KB | Thousands of 4-20 mA, PT100, 0-10 V channels |
| ET 200SP (station) | 1 head, up to 64 modules | per head | Up to 512 per station with AI 8 modules |
A plant with a central S7-1500 and 6 field panels, each with an ET 200SP of 96 DI, 48 DO and 16 AI: about 960 signals in total. It uses under 1% of the CPU's address range. A 7th panel is added later with a single cable.
From the screen on the panel door to the control centre of a city, all the solutions are WinCC. Unified screens are built in TIA Portal the same way whether they run on a panel or a PC, so a load screen built for the panel is reused in the SCADA.
| Solution | Where it runs | Suitable for | Expansion |
|---|---|---|---|
| Unified Basic Panel | Touch screen on the panel | Small machines, pumping stations | Upgrade to Comfort with the same project |
| Unified Comfort Panel | 7" to 22" touch screen | Plant operation, alarms, trends | Web access, Edge apps on the panel |
| WinCC Unified PC | Industrial PC or server | Installation SCADA, many PLCs | Web clients, SQL history, redundant server |
| WinCC V8 (Professional) | PC | Existing SCADA systems being maintained | Gradual migration to Unified |
| WinCC Open Architecture | Multiple servers, Windows or Linux | Water and energy networks, very large systems | Distributed systems with thousands of stations |
WinCC on a PC is licensed by PowerTags, meaning the tags connected to a PLC. The screen's internal tags do not count. The customer buys a licence for the size they have today and, when loads or stations are added, buys only the difference (PowerPack). The project, the screens and the history stay as they are.
Example with indicative values; change the fields. Licence sizes are indicative and change with the WinCC version; the exact licence is chosen from the current Siemens price list.
SIMATIC is not a closed system tied to one installer. It is one of the most widespread automation systems in the world, and the customer has complete freedom over who sells them the hardware and who maintains the installation.
SIMATIC does not lock the customer in. It speaks the industry standards, so it accepts equipment from other manufacturers and sends data to third-party software.
The platform is chosen per project. SIMATIC is a frequent choice, but we also work with other systems, depending on the needs and the equipment the customer already has.
Signal limits, expansion limits and PowerTags packages are indicative and confirmed per project; they depend on the CPU and the head selected. For each project the final configuration is checked in the TIA Selection Tool. Product names belong to Siemens AG. A note by KP AUTOMATION.
Tell us the size and your needs and we will propose the right configuration.