S7-1200 VS S7-1500
S7-1200 vs S7-1500: Which Siemens PLC to Choose
How Siemens' basic and advanced PLCs differ, what the second-generation S7-1200 G2 changed, and a step-by-step way to choose, with every spec taken from Siemens' own manuals and launch material.
The S7-1200 is Siemens' basic PLC for compact machines, and the S7-1500 is its advanced, modular PLC for mid-range to large machines and plants. Choose the S7-1200 (now the second-generation S7-1200 G2) when a machine needs up to 31 PROFINET devices, a handful of motion axes and a small footprint. Choose the S7-1500 when you need much more memory, more devices and axes, a diagnostic display on the CPU or redundant controllers. Both are programmed in TIA Portal, so the skills carry over.
Checked on 11 October 2026 against the sources listed under this post.
What is the difference between the S7-1200 and the S7-1500?
The S7-1200 is a compact controller with on-board I/O that clips onto a DIN rail and takes a few signal modules to its right. Siemens calls it its basic controller. The S7-1500 is a modular controller system built for higher performance: the CPU sits on a mounting rail with I/O modules beside it. Siemens' S7-1500 product page says several CPU versions are available, each in several performance classes, and the range covers standard, compact, fail-safe, technology and redundant CPUs.
In Siemens' own launch slides for the G2, the two families sit on one chart: the S7-1200 and S7-1200 G2 as the basic controller, the S7-1500 above them as the advanced controller, with application complexity rising from one to the other. The decision is less about which is better and more about how big and demanding the machine is.
What does the S7-1500 add over the S7-1200?
The headline differences, all from Siemens' May 2024 CPU 1511C-1 PN equipment manual, which lists the whole S7-1500 range:
- A display on every CPU. All S7-1500 CPUs have a plain-text display showing order numbers, firmware and serial numbers of connected modules, diagnostic alarms in plain text, and IP settings you can change without a laptop. On the CPU 1511C it is a 3.45 cm screen with eight keys.
- Integrated system diagnostics, on by default. Diagnostics are configured rather than programmed, and the same plain-text alarms appear on the CPU display, in STEP 7, on the HMI and in the web server, even in STOP mode.
- Much more memory and speed. Work memory runs from 1.8 MB on the CPU 1511-1 PN to 66 MB on the CPU 1518-4 PN/DP, and bit operations from 25 ns down to 1 ns.
- Redundancy. The S7-1500R/H CPUs (1513R, 1515R, 1517H and the fail-safe 1518HF) give high-availability systems. There is no redundant S7-1200.
- Technology CPUs. The S7-1500T range is built for drive control; Siemens' product page says they add extended gear synchronisation, cyclic cams, and kinematics and portal handling.
- Fail-safe CPUs across the range, certified up to SIL 3 to IEC 61508 and PL e, Category 4 to ISO 13849-1.
In this video, Siemens Knowledge Hub presents the integrated system diagnostics of the SIMATIC S7-1500, the feature maintenance teams notice first when they move up from an S7-1200. It is one of the lessons in our free PLC and Electrical Troubleshooting for Maintenance Teams course, and it is worth six minutes because diagnostics is where the two families feel most different on a real plant floor.
S7-1200 G2 vs S7-1500: the specifications side by side
The fairest comparison is between two compact CPUs with on-board I/O: the S7-1200 G2 CPU 1214C and the S7-1500 CPU 1511C-1 PN. G2 figures come from Siemens' S7-1200 G2 flyer and launch slides; S7-1500 figures from the equipment manual.
| Feature | S7-1200 G2 CPU 1214C | S7-1500 CPU 1511C-1 PN |
|---|---|---|
| Work memory | 250 kB program, 750 kB data | 300 kB program, 1.5 MB data |
| Bit operation time | 37 ns | 25 ns |
| On-board I/O | 14 DI, 10 DQ (analogue via signal board) | 16 DI, 16 DQ, 5 AI, 2 AO |
| PROFINET | 2 ports, IRT, up to 31 devices | 2 ports, IRT, up to 128 IO devices |
| Positioning axes (4 ms cycle) | 4 typical, 10 maximum | 11 typical |
| High-speed counters | 8 | 6 |
| CPU display | None; NFC for phone access | 3.45 cm display, 8 keys |
| Expansion | Up to 10 modules (SM plus CM), 2 signal boards | Modular S7-1500 I/O |
| Engineering | STEP 7 Basic, TIA Portal V20 or later | TIA Portal V19 or later (firmware V3.1) |
Two things stand out. First, the G2 closed much of the raw-speed gap at the small end: 37 ns against 25 ns. Second, the S7-1500 still pulls away on scale. One CPU 1511C interface takes up to 128 IO devices and, in total, up to 512 distributed I/O devices across AS-i, PROFIBUS or PROFINET; the G2 stops at 31 PROFINET devices. Further up the range the gap widens: the CPU 1518-4 PN/DP MFP has 116 MB of work memory (50 MB of it reserved for the CPU runtime library) and runs C/C++ blocks in the user program.
What is the S7-1200 G2, and what changed from the S7-1200?
The S7-1200 G2 is the second generation of the S7-1200, shown at Hannover Messe in April 2024. Siemens' press release of 6 June 2024 called it the first new controller generation from Siemens in ten years, with availability at the end of 2024. Siemens' launch slides list the first CPUs (1212C, 1212FC, 1214C, 1214FC) as the initial release with TIA Portal V20.
Siemens' flyer says the G2 has twice the performance and memory of the S7-1200. The migration slides compare the CPU 1214C of each generation:
| CPU 1214C | S7-1200 (first generation) | S7-1200 G2 |
|---|---|---|
| Program and data memory | 150 kB | 250 kB program, 750 kB data |
| Bit performance | 85 ns | 37 ns |
| High-speed counters | 6 | 8 |
| Integrated analogue inputs | 2 | None; optional signal board |
| Width | 110 mm | 80 mm |
| PROFINET | 1 or 2 ports, by CPU | 2 ports on every CPU, IRT |
| Fail-safe engineering | Separate STEP 7 Safety Basic licence (to V19) | Included in STEP 7 Basic from V20 |
Other changes Siemens lists: NFC access to diagnostic and device data, even with the CPU unpowered; support for Media Redundancy Protocol (MRP) and MRPD; up to two signal boards in the CPU; motion technology objects based on the SIMATIC Motion Library V8.0, including synchronous axes, cams and simple kinematics; and IEC 62443-4-2 certification for industrial cybersecurity.
The G2 also has a new hardware design with push-in terminals and its own range of signal modules, so a migration is a hardware change, not a CPU swap. Siemens offers a migration tool as a TIA Portal add-in. On its migration page, Siemens gives 1 November 2026 for the official phase-out announcement of the first generation, 31 October 2027 as the last date to order it new, and spare parts until about 2036. For new designs, the comparison that matters is now S7-1200 G2 vs S7-1500.
S7-1200 or S7-1500: how to choose in seven steps
- Count the network. List every drive, remote I/O station, HMI and instrument on PROFINET. Over 31 devices points to the S7-1500.
- List the motion. Speed axes, positioning, synchronous axes and simple kinematics fit the G2 within its motion budget (typically 4 positioning axes at a 4 ms cycle and 35% CPU load, at most 10). Many axes, or advanced gearing and cams across controllers, point to the S7-1500 or S7-1500T.
- Decide the safety concept. Both families have fail-safe CPUs. Check the certified level on the data sheet of the exact F-CPU you plan to use.
- Ask about availability. If an unplanned stop costs more than a second controller, only the S7-1500R/H gives you CPU redundancy.
- Size memory for data, not just logic. Recipes, large data blocks, OPC UA and trace data fill memory faster than ladder rungs.
- Weigh panel space and licences. A G2 CPU 1214C is 80 mm wide, and STEP 7 Basic is, in Siemens' words on its STEP 7 page, the price-optimised subset of STEP 7 Professional. In practice the S7-1500 needs Professional.
- Validate the design. Siemens' TIA Selection Tool checks a configuration before you order.
What about S7-1200 vs S7-1500 price?
Siemens does not publish list prices on the product pages we read, and the price of the same CPU varies by distributor, country and project discount, so we give no figure. Compare total cost rather than the CPU line: the CPU, I/O modules, the STEP 7 edition (Basic or Professional), any safety engineering (for the G2, included in STEP 7 Basic from V20), panel space and engineering time. A G2 can be the cheaper machine controller and still be the wrong choice if the project outgrows it in two years.
Which should you learn first?
Learn the S7-1200 first. It is the controller in most training kits and it teaches the full TIA Portal workflow: hardware configuration, tags, LAD, FBD and SCL, PLCSIM and online diagnostics. Our free Siemens S7-1200 with TIA Portal tutorial series starts there, and your first S7-1200 program walks through the first project step by step. Then move to Siemens S7-1500 Advanced Programming in TIA Portal for the larger CPU's diagnostics and program structure, or take the broader Siemens TIA Portal course.
You do not need hardware or a paid licence to start: our guide to the TIA Portal free trial licence explains what the trial covers, and what is new in TIA Portal V21 covers the latest release, which supports the S7-1200 G2. For a wider route through Siemens skills, see our Siemens PLC training guide.
All of the learning is free. If you want proof of completion, the optional EDWartens Certificate of Completion costs US$8.99 for a beginner course; it is not a Siemens certification and not accredited, and anyone can check it at edwartens.com/verification.
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Questions
What is the main difference between the S7-1200 and the S7-1500?
Scale. Siemens sells the S7-1200 as its basic controller for compact machines and the S7-1500 as its advanced controller for mid-range to large machines and plants. The S7-1500 offers far more memory, more PROFINET devices and axes, a display on every CPU, and redundant R/H CPUs. Both are programmed in TIA Portal.
What is the S7-1200 G2?
The S7-1200 G2 is the second generation of Siemens' basic PLC, shown at Hannover Messe in April 2024 and announced on 6 June 2024 as Siemens' first new controller generation in ten years. Siemens says it doubles the performance and memory of the original S7-1200, and it adds NFC, two PROFINET ports on every CPU and more motion control. It first shipped with TIA Portal V20.
Is the S7-1200 being discontinued?
The first generation is being phased out. Siemens' migration page gives 1 November 2026 as the official phase-out announcement, 31 October 2027 as the last date to order it as a new device, and spare parts until about 2036. Siemens recommends the S7-1200 G2 for new projects.
Is the S7-1500 more expensive than the S7-1200?
Generally yes: Siemens positions the S7-1200 as the cost-optimised basic controller and the S7-1500 as the advanced one, and STEP 7 Basic is the lower-priced subset of STEP 7 Professional. Siemens does not publish list prices on the product pages we read, and prices vary by distributor and region, so ask a distributor for a quote on the exact article numbers.
Can S7-1200 code be moved to an S7-1500?
Largely, because both use the same TIA Portal languages: LAD, FBD, SCL and the same instruction style. Hardware configuration, addresses and some instructions need checking, and a few instructions and technology objects differ between the families. Siemens also offers a separate TIA Portal add-in for migrating first-generation S7-1200 projects to the S7-1200 G2.
Which should a beginner learn first, S7-1200 or S7-1500?
Start with the S7-1200, because it is the controller most training kits use and it teaches the same TIA Portal workflow. Everything you learn carries over to the S7-1500, where you then add its diagnostics, larger programs and technology functions. PLCSIM lets you practise both without hardware.
Sources
- Siemens press release: New generation of Simatic S7-1200 G2 controllers (6 June 2024)
- Siemens: SIMATIC S7-1200 G2, new basic PLC generation (product page, read 11 October 2026)
- Siemens: SIMATIC S7-1200, end of lifecycle for the first generation (migration page, read 11 October 2026)
- Siemens: SIMATIC S7-1200 G2 flyer with ordering information (February 2025)
- Siemens: SIMATIC S7-1200 G2 Deep Dive Launch Webinar slides (2025, hosted by APS Industrial)
- Siemens: SIMATIC S7-1500 CPU 1511C-1 PN Equipment Manual, A5E40898565-AC (May 2024)
- Siemens: SIMATIC S7-1500 advanced controller (product page, read 11 October 2026)
- Siemens: STEP 7 (TIA Portal) Basic and Professional (product page, read 11 October 2026)
Written by the EDWartens engineering team for general education. Product names are trademarks of their owners; mentioning them does not imply endorsement. Prices and terms of other providers were checked on the date shown and can change.
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