PLC · 8 min read · Updated November 2026
SIMATIC S7-1200 G1 vs G2: What Actually Changed and When to Switch
Siemens released the second-generation S7-1200 in 2024 and announced the phase-out of the first generation from November 2026. The G2 is faster, has more memory and native OPC UA, but it is not a drop-in: different signal modules, different TIA Portal version, different ordering numbers. What a machine builder and a plant maintainer need to know.
The S7-1200 is the most common small PLC in the world, and its first generation (CPU 1211C–1217C, order numbers 6ES7 2xx-xxx40-0XB0 and later) has been shipping since 2009 with several hardware revisions. The S7-1200 G2 (order numbers 6ES7 2xx-xxx50-0XB0 with the G2 designation) arrived with TIA Portal V20 in 2024. Siemens announced PM400 (phase-out) for the G1 effective 1 November 2026, with the usual long spares tail. This is not an S7-300-style crisis — G1 CPUs will be purchasable for a while and spares for years — but anyone standardising a machine or stocking spares today should understand what changed.
What the G2 improves
- Performance. Bit operations roughly ten times faster, more work memory (up to 500 KB on the 1217 class versus 150 KB on G1), and more data blocks per project.
- Communications. Dual-port PROFINET on more CPUs, OPC UA server built in (G1 did not have it), Modbus TCP and S7 communication as before, plus web server with user-defined pages.
- Motion. Up to eight axes with technology objects, higher-frequency pulse outputs, and better support for PROFIdrive drives such as SINAMICS G120/V90.
- Security. Password-protected access levels, TLS-secured communication, and the TIA Portal V20 security concept (user management, certificate handling) are mandatory concepts rather than options.
- Hardware. Removable front connectors on the CPU (G1 had fixed terminals on the CPU), new signal modules (SM 1221/1222/1223/1231 G2 variants with the 50 suffix), new communication modules and a different signal board family.
What does not carry over
| Item | G1 | G2 | Practical effect |
|---|---|---|---|
| Signal modules | 6ES7 22x/23x-…-0XB0 (G1) | G2-specific SMs | G1 SMs do not plug into a G2 CPU and vice versa — a spare SM must match the generation |
| Signal boards | SB 12xx | New SB family | Same |
| Communication modules | CM 1241 (serial), CM 1243-5 (DP), CP 1243-x | G2 CM/CP family | Same; check availability of the exact function (e.g. DP master) on G2 before migrating |
| Engineering | TIA Portal V13–V19 | TIA Portal V20 and later | Project upgrade required; V20 drops some older features and needs Windows 10/11 64-bit |
| Memory card | SIMATIC MC | SIMATIC MC (same family) | Reusable, but the project is tied to the CPU type |
| Dimensions | CPU 1214C: 110 mm wide | Similar width, slightly different depth and connector positions | Panel usually fine; check wire lengths because of removable connectors |
| HMI | Basic/Comfort panels | Same panels supported | No change; KTP700 Basic works with both |
The practical consequence for maintenance: a plant with 30 G1 S7-1200 machines cannot hold "an S7-1200 spare"; it holds G1 spares, and when the first G2 machine arrives it holds G2 spares too. For machine builders the consequence is a standardisation decision, and the right answer in 2026 is to design new machines on G2 — the G1 will stop being orderable within the life of a machine series.
Migrating a G1 project to G2
TIA Portal V20 upgrades the project and offers "change device" from a G1 CPU to the corresponding G2 CPU. The program converts without changes in almost every case (same instruction set, same block types); what needs attention is the hardware configuration (every SM and SB re-selected as G2 type and re-addressed), the PROFINET device names and IP addresses (unchanged if you keep them), any web-server user pages (new API) and the security settings that V20 enforces — the CPU must have an access-level configuration before it will run. Allow half a day for a typical machine including a test run. For OEM machine series the one-time effort is small compared with the benefit of OPC UA and the faster CPU.
When to switch
- New machine designs: G2 now. The G1 is already in phase-out; shipping new machines on it means your customers inherit an obsolescence problem.
- Existing machines: do not migrate for its own sake. Keep G1 spares (CPU plus the SMs used, one set per 5–10 machines) and migrate when a machine is being rebuilt or when OPC UA / performance is needed.
- Fleet maintenance: record the generation on every machine's asset record and in the spares list. The order-number suffix tells you (…40-0XB0 and earlier revisions = G1; G2 CPUs carry the G2 marking and new order numbers).
Alternatives worth knowing
If you are re-evaluating the small-PLC standard anyway: the S7-1200 G2 competes with the Mitsubishi FX5U, Omron NX1P2, Delta AS200 and LS XGB-U at similar prices; the ET 200SP CPU (1510SP/1512SP) is the choice when you want S7-1500 features in a distributed-I/O footprint; and for S7-1500 class performance in a small machine the CPU 1511C compact is the step up. We stock G1 and G2 CPUs and signal modules and quote both generations side by side with lead times.
A migration walkthrough
Take a typical G1 machine: CPU 1214C DC/DC/DC, SM 1223 16DI/16DO, SM 1231 4AI, CM 1241 RS485 for a Modbus RTU drive, KTP700 Basic, project in TIA Portal V16. Steps in V20: open and upgrade the project (V20 performs the upgrade in one pass from V16 and later; older versions must be stepped through V17 first); in the device view, right-click the CPU and "change device" to CPU 1214C G2; TIA retains the program, tags, OBs and PLC data types; replace each SM with its G2 counterpart from the hardware catalogue and re-enter the I/O start addresses (keep them identical to avoid touching the program); replace the CM 1241 with the G2 serial module and check that the Modbus_Comm_Load/Modbus_Master instructions compile against it; set the access level and the PLC user management, which V20 requires before download; compile, download, and run the machine through its sequence. Expect two to four hours for a machine of this size, most of it in the hardware catalogue and the test run. Where the G1 used a signal board (SB 1232 analog output is common), check that the G2 signal board family has the equivalent; if not, an SM module takes its place and needs a slot.
Performance in practice
Machine builders ask whether the G2 speed matters. For a packaging machine with a 10 ms cycle target it does: a G1 1214C running a large FBD program with several hundred networks may sit at 8–12 ms scan; the same program on a G2 drops to 1–2 ms, which lets you move more logic into the PLC instead of a dedicated motion controller, use faster cyclic interrupts, and add OPC UA without affecting the cycle. The memory increase matters for anyone who hit the 100 KB load-memory ceiling on the 1214C — recipe data blocks and web server pages no longer compete with the program.
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Quick answers
Can I use my G1 signal modules with a G2 CPU?
No. The G2 CPU has its own generation of signal modules, signal boards and communication modules. Spares must match the generation, so record it on the asset list.
Which TIA Portal version does the S7-1200 G2 need?
TIA Portal V20 or later. G1 CPUs with the latest firmware are also supported in V20, so one engineering station can maintain both.
Will the S7-1200 G1 still be available after November 2026?
PM400 is the phase-out announcement; the product remains orderable until the PM410 cancellation date, which Siemens announces separately, and spares continue afterwards. Stock G1 spares for installed machines now rather than later.