Siemens S7-1200 — compact PLC with a powerful ecosystem
The S7-1200 is a compact controller from Siemens that has become the standard for mid-range automation projects across Europe and Ukraine. Built-in Ethernet (PROFINET), web server, TIA Portal programming — all in a housing starting at 90 mm wide. If your customer demands "Siemens or nothing" — the S7-1200 covers 90% of typical tasks.
We install S7-1200 on sites that require Siemens-level reliability without the S7-1500 price tag. Bottling lines, pump stations, HVAC systems, boiler rooms — anywhere the I/O count stays under 200-300 points.
S7-1200 model range: from CPU 1211C to 1217C
The series includes 5 CPU models differing in built-in I/O count and memory size. All run on the same TIA Portal platform and support the same instruction set.
| Model | DI/DO | AI | Work memory | Load memory |
|---|---|---|---|---|
| CPU 1211C | 6DI / 4DO | 2 | 50 KB | 1 MB |
| CPU 1212C | 8DI / 6DO | 2 | 75 KB | 1 MB |
| CPU 1214C | 14DI / 10DO | 2 | 100 KB | 4 MB |
| CPU 1215C | 14DI / 10DO | 2AI + 2AO | 125 KB | 4 MB |
| CPU 1217C | 14DI / 10DO | 2AI + 2AO | 150 KB | 4 MB |
CPU 1214C is the most popular choice. 14 digital inputs, 10 outputs, 2 analog inputs, and 100 KB of work memory. This is enough for most tasks involving PID control, metering, and basic positioning.
Programming in TIA Portal: what you need to know
TIA Portal is the unified development environment for all Siemens controllers (S7-1200, S7-1500, ET 200SP). This is both an advantage and a drawback: advantage — everything in one place; drawback — the license starts at $500 for the basic version.
- Programming languages: LAD (Ladder), FBD, SCL (Structured Control Language — similar to ST), Graph (SFC)
- Simulation: built-in PLCSIM — test your program without real hardware
- Versions: TIA Portal V17-V19 for S7-1200 V4.x
- Licensing: Basic (free for S7-1200) / Professional (paid, full functionality)
SCL (Structured Control Language) is probably the most convenient language for S7-1200. It resembles Pascal and lets you write complex logic more compactly than Ladder. But for simple relay circuits, LAD is still clearer — especially for maintenance staff on site.
More on PLC programming languages: IEC 61131-3 standard.
S7-1200 communication capabilities
The main advantage of S7-1200 over competitors in this price range is built-in PROFINET. This is Siemens' industrial Ethernet protocol that provides connectivity to HMI panels, other PLCs, and distributed I/O without extra modules.
- PROFINET: 1-2 RJ-45 ports (depending on CPU), up to 16 connections
- PROFIBUS: via CM 1243-5 communication module
- RS-485/RS-232: via CB 1241 (RS-485) or CM 1241 modules
- Modbus TCP: built-in (via PROFINET port)
- Modbus RTU: via RS-485 module
- OPC UA: built-in server (firmware V4.2+)
OPC UA is a protocol that allows S7-1200 to exchange data with SCADA systems, cloud platforms, and PLCs from different manufacturers. For Industry 4.0 and IoT applications, this is a strong argument for Siemens.
Compared to Delta DVP or Mitsubishi FX5U, S7-1200 wins specifically through its ecosystem: PROFINET + TIA Portal + PLCSIM + web server. But the price reflects this — CPU 1214C costs $350-500, while Delta DVP-SA2 is $150-250.
Expansion modules and signal boards
S7-1200 expands in three ways: signal modules (SM) to the right of the CPU, signal boards (SB) in a slot on the CPU front panel, and communication modules (CM) on the left.
- Signal modules (SM): DI, DO, combined DI/DO, AI, AO — up to 8 modules per CPU
- Signal boards (SB): compact boards that plug directly into the CPU — add 2-4 I/O without increasing width
- Communication modules (CM): RS-485, RS-232, PROFIBUS, USS protocol for Siemens VFDs
Maximum configuration for a single S7-1200: up to 284 digital I/O + 51 analog channels. For most projects, this is more than enough. If you need more, move to S7-1500 or ET 200SP distributed I/O.
General overview of expansion modules for various PLCs: PLC expansion modules.
Typical S7-1200 applications in Ukraine
Based on our experience, S7-1200 is most commonly installed on:
- Boiler rooms and HVAC: PID temperature control, pump management, heat metering. CPU 1214C + analog modules + HMI KTP700
- Pump stations: automatic pump switching, dry-run protection, pressure sensor integration. CPU 1212C + RS-485 for Modbus
- Conveyor lines: discrete control + positioning. CPU 1214C + Sinamics V20 VFDs via USS
- Water treatment: multi-stage filtration, chemical dosing. CPU 1215C with analog outputs
If your project involves integration with other Siemens equipment (Sinamics VFDs, Comfort panels, WinCC SCADA) — S7-1200 is the natural choice. Everything works out of the box through TIA Portal without converters or gateways.
Frequently Asked Questions
How much does a Siemens S7-1200 cost?
CPU 1211C (minimum) — from $200, CPU 1214C (most popular) — $350-500, CPU 1215C (with analog outputs) — $500-700. Prices depend on the supplier and exchange rates. Add $150-300 per expansion module.
Can S7-1200 be programmed for free?
Yes. TIA Portal Basic is a free version that lets you program S7-1200 and basic HMI panels. Limitations: no SCL, no OPC UA configuration, no PLCSIM. For full functionality, you need TIA Portal Professional (from $500).
What is the difference between S7-1200 and S7-1500?
S7-1500 is the higher series with more memory (up to 6 MB), better performance (1 ns per bit), PROFINET IRT support, and Safety Integrated. S7-1200 is for tasks with fewer than 300 I/O; S7-1500 is for large systems and Motion Control.
Does S7-1200 support Modbus?
Yes. Modbus TCP is built-in (via the PROFINET port, no additional module needed). Modbus RTU works through an RS-485 module (CB 1241 or CM 1241). S7-1200 can be both Master and Slave.
How many I/O can be connected to S7-1200?
Maximum 284 digital I/O and 51 analog channels with expansion modules. For distributed I/O via PROFINET, the protocol limit is 16 devices. In practice, for systems exceeding 300 I/O, S7-1500 is the better choice.
Summary
S7-1200 is a PLC for those who value the Siemens ecosystem: TIA Portal, PROFINET, PLCSIM, web server, OPC UA. In terms of features, it falls behind Mitsubishi FX5U on memory but wins on communications and integration. The price is higher than Delta DVP, but for projects specifying Siemens — there is no alternative.
Browse the Siemens PLC catalog with prices. Need help choosing a model? Contact us — we will select the right CPU and modules for your task.
