Compact control
When S7-1200 makes sense
Choose S7-1200 for compact machines, moderate I/O, standard sequence control, basic motion or PID, and projects where panel space and initial cost matter.
Siemens automation selection guide
Siemens S7-1200 vs S7-1500: Which PLC Should You Choose?
Compare Siemens S7-1200 and S7-1500 controllers, explore 50 commonly requested models, and plan your next automation project with confidence.
Start with the application
Two PLC families. Different project priorities.
S7-1200 is a compact choice for standard machine automation. S7-1500 is built for more demanding, scalable systems with higher performance and broader diagnostics.
Advanced automation
When S7-1500 makes sense
Choose S7-1500 for larger programs, distributed I/O, demanding communication, advanced motion, system-wide diagnostics, or planned future expansion.
Introduction
Siemens S7-1200 vs S7-1500: Which PLC Should You Choose?
Choosing between the Siemens S7-1200 and S7-1500 is a common decision for machine builders, system integrators, and industrial automation buyers. Both families are engineered through TIA Portal, but they target different levels of machine complexity, performance, expandability, and system requirements.
The S7-1200 is generally a compact and cost-effective solution for small and medium-sized machines. The S7-1500 is designed for more demanding systems that require higher performance, broader scalability, advanced diagnostics, and more sophisticated control functions.
The right choice depends on I/O requirements, communication architecture, motion control, future expansion, and total project cost.
Product overview
What are the Siemens S7-1200 and S7-1500?
S7-1200 compact machine control
The S7-1200 combines a compact CPU with integrated I/O options and expansion through signal boards, signal modules, and communication modules.
- Packaging machines
- Conveyors and material handling
- Pumps and compressors
- Small water treatment systems
- Simple assembly and HVAC equipment
S7-1500 modular automation
The S7-1500 is a modular, high-performance platform for complex machines and plant automation. It supports CPUs, signal modules, technology modules, communication modules, and distributed I/O.
- Large packaging lines
- Robotics and handling systems
- High-speed manufacturing
- Process automation
- Production lines with distributed I/O
System architecture
How a Siemens PLC system is connected
A typical system can include a programming device with TIA Portal, a PLC CPU, an HMI panel, and distributed I/O connected over Industrial Ethernet or PROFINET.
Illustrative architecture: TIA Portal PC, S7-1500 CPU, HMI, ET 200SP, and ET 200MP distributed I/O.
I/O wiring concept
Example PLC wiring layout
Sensors connect to digital or analog inputs, actuators connect to digital or analog outputs, and HMI or drives communicate through the configured network.
Illustrative wiring concept only. Terminal numbers, grounding, shielding, fuses, and safety circuits must follow the selected module manual and local electrical standards.
Selection checklist
What should you check before ordering?
01 · I/O
Count DI, DO, AI, AQ and special signals.
02 · Network
List HMI, drives, remote I/O and protocols.
03 · Motion
Confirm axes, cycle time and technology objects.
04 · Growth
Reserve capacity for expansion and service.
| REQUIREMENT | USUALLY POINTS TOWARD S7-1200 | USUALLY POINTS TOWARD S7-1500 |
|---|---|---|
| Machine size | Compact or stand-alone | Complex or multi-station |
| Expansion | Limited and predictable | Distributed and expandable |
| Diagnostics | Standard local diagnostics | System-wide diagnostics |
| Motion | Basic positioning or counting | Advanced synchronized motion |
Engineering comparison
S7-1200 vs S7-1500
Use this table as a first selection step. Final selection depends on CPU, firmware, modules, TIA Portal version, and the complete machine architecture.
| REQUIREMENT | S7-1200 | S7-1500 |
|---|---|---|
| Best fit | Compact and medium-sized machines | Complex machines and plant automation |
| Architecture | Compact CPU with integrated I/O options | Modular CPU, signal, technology and communication modules |
| Expansion | Limited to moderate expansion | Designed for larger and distributed expansion |
| Diagnostics | Standard CPU and module diagnostics | System-wide diagnostics across TIA Portal, HMI, Web server and CPU display |
| Motion and technology | Basic to intermediate requirements, depending on CPU | Advanced motion and technology applications |
| Budget | Often lower initial hardware cost | Higher investment where performance and scalability justify it |
Need help selecting a PLC?
Send us your I/O list.
Share your application, I/O count, drives, communication protocols, and existing PLC model. We can help you compare S7-1200 and S7-1500 and prepare a configuration for quotation.
Questions buyers ask
Frequently asked questions
Is S7-1500 always better than S7-1200?
No. S7-1500 offers more performance and scalability, but S7-1200 is often the more appropriate and economical choice for compact, clearly defined machines.
Which PLC is suitable for a packaging machine?
S7-1200 fits compact packaging machines with moderate I/O and motion needs. S7-1500 is better suited to larger multi-axis lines, distributed I/O, high-speed processing and extensive diagnostics.
Can the models be programmed in TIA Portal?
Yes. Both families are engineered in TIA Portal. The required TIA Portal version depends on the exact CPU article number and firmware version.
What should I send before asking for a quotation?
Send the complete Siemens MLFB or order number, quantity, destination, condition preference, required delivery date, nameplate photo and any firmware or project-version requirement.
Can S7-1200 and S7-1500 use the same TIA Portal project?
They can be configured in the same TIA Portal environment, but changing CPU families requires hardware reconfiguration and may require program, communication and technology-object changes.
Can I use S7-1200 for a machine with a VFD?
Yes. An S7-1200 can control a VFD through digital and analog signals or supported industrial networks. Confirm the CPU, drive, communication interface and required control functions.
When should I choose a fail-safe S7-1200F or S7-1500F?
Choose an F-CPU when the machine risk assessment requires safety functions such as emergency stop, guard monitoring or safe drive control to be handled by a certified fail-safe control system.
Is S7-1200 suitable for remote I/O?
Yes, when the selected CPU and PROFINET configuration support the required distributed I/O architecture. Confirm device count, update time, topology and supported interface modules.
Is S7-1500 suitable for SCADA communication?
Yes. S7-1500 is commonly used with SCADA systems through PROFINET, Industrial Ethernet, OPC UA or communication processors, depending on the CPU and project architecture.
Can I replace an older Siemens PLC with S7-1200 or S7-1500?
A migration is possible in many cases, but it is not normally a drop-in replacement. Review the original program, I/O, wiring, networks, motion functions, HMI, mounting and licenses.
How many I/O points should I reserve for future expansion?
The reserve depends on the project, but the design should include spare channels, panel space, power capacity and network capacity for realistic future additions.
What is the difference between a transistor output and a relay output?
Transistor outputs switch DC loads quickly and support high switching frequency. Relay outputs provide galvanic isolation and can switch AC or DC loads, but they operate more slowly and have mechanical contact life limits.
Does the CPU model determine the complete PLC price?
No. Total cost also depends on signal modules, communication and technology modules, power supplies, memory, connectors, distributed I/O, HMI, software and engineering requirements.
What information is needed for a Siemens PLC quotation?
Provide the full MLFB, quantity, CPU and firmware, I/O list, network protocols, power supply, safety requirements, accessories, delivery country and required condition.
Model finder
50 commonly requested Siemens models
Search by model, family, or application. This preview uses family-level names; confirm the complete MLFB, suffix, firmware, and lifecycle status before purchase.
| # | FAMILY | COMMON MODEL | FULL MLFB / ORDER NUMBER | TYPE | TYPICAL USE |
|---|---|---|---|---|---|
| 1 | S7-1200 | CPU 1211C DC/DC/DC | 6ES7211-1AE40-0XB0 | Standard CPU | Small stand-alone machines |
| 2 | S7-1200 | CPU 1212C DC/DC/DC | 6ES7212-1AE40-0XB0 | Standard CPU | Small automation equipment |
| 3 | S7-1200 | CPU 1214C DC/DC/DC | 6ES7214-1AG40-0XB0 | Standard CPU | Packaging and pump systems |
| 4 | S7-1200 | CPU 1215C DC/DC/DC | 6ES7215-1AG40-0XB0 | Standard CPU | Medium machines and dual-network projects |
| 5 | S7-1200 | CPU 1217C DC/DC/DC | 6ES7217-1AG40-0XB0 | Standard CPU | High-speed counting and complex machines |
| 6 | S7-1200 | CPU 1212FC | 6ES7212-1AF40-0XB0 | Fail-safe CPU | Small safety systems |
| 7 | S7-1200 | CPU 1214FC | 6ES7214-1HF40-0XB0 | Fail-safe CPU | Medium safety machines |
| 8 | S7-1200 | CPU 1215FC | 6ES7215-1HF40-0XB0 | Fail-safe CPU | Integrated standard and safety control |
| 9 | S7-1200 | SM 1221 | 6ES7221-1BF32-0XB0 | Digital input module | DI expansion |
| 10 | S7-1200 | SM 1222 | 6ES7222-1BF32-0XB0 | Digital output module | DO expansion |
| 11 | S7-1200 | SM 1223 | 6ES7223-1BH32-0XB0 | Digital I/O module | Mixed DI/DO expansion |
| 12 | S7-1200 | SM 1231 AI | 6ES7231-4HD32-0XB0 | Analog input module | Pressure, level and temperature signals |
| 13 | S7-1200 | SM 1232 AQ | 6ES7232-4HB32-0XB0 | Analog output module | Valves and drives |
| 14 | S7-1200 | SM 1234 AI/AQ | 6ES7234-4HE32-0XB0 | Mixed analog module | Small process systems |
| 15 | S7-1200 | SM 1231 TC | 6ES7231-5QD32-0XB0 | Thermocouple module | Temperature measurement |
| 16 | S7-1200 | SM 1231 RTD | 6ES7231-5PF32-0XB0 | RTD module | Precision temperature measurement |
| 17 | S7-1200 | SB 1221 | 6ES7221-3BD30-0XB0 | Signal board | Compact DI expansion |
| 18 | S7-1200 | SB 1222 | 6ES7222-3BD30-0XB0 | Signal board | High-speed pulse output |
| 19 | S7-1200 | SB 1223 | 6ES7223-3BD30-0XB0 | Signal board | Compact DI/DO expansion |
| 20 | S7-1200 | SM 1278 4xIO-Link Master | 6ES7278-4BD32-0XB0 | IO-Link master | Smart sensor connectivity |
| 21 | S7-1500 | CPU 1511-1 PN | 6ES7511-1AL03-0AB0 | Standard CPU | Small to medium automation |
| 22 | S7-1500 | CPU 1513-1 PN | 6ES7513-1AM03-0AB0 | Standard CPU | Medium applications |
| 23 | S7-1500 | CPU 1515-2 PN | 6ES7515-2AN03-0AB0 | Standard CPU | Complex medium machines |
| 24 | S7-1500 | CPU 1516-3 PN/DP | 6ES7516-3AP03-0AB0 | Standard CPU | High-end machines and PROFIBUS |
| 25 | S7-1500 | CPU 1517-3 PN/DP | 6ES7517-3AP00-0AB0 | Standard CPU | High-end automation and communication |
| 26 | S7-1500 | CPU 1518-4 PN/DP | 6ES7518-4AP00-0AB0 | High-performance CPU | Large lines and demanding communication |
| 27 | S7-1500 | CPU 1511F-1 PN | 6ES7511-1FL03-0AB0 | Fail-safe CPU | Small safety automation |
| 28 | S7-1500 | CPU 1513F-1 PN | 6ES7513-1FM03-0AB0 | Fail-safe CPU | Medium safety machines |
| 29 | S7-1500 | CPU 1515F-2 PN | 6ES7515-2FN03-0AB0 | Fail-safe CPU | Complex machine safety |
| 30 | S7-1500 | CPU 1516F-3 PN/DP | 6ES7516-3FP03-0AB0 | Fail-safe CPU | Large safety automation |
| 31 | S7-1500 | CPU 1518F-4 PN/DP | 6ES7518-4FP00-4AB0 | High-performance safety CPU | High-end safety production lines |
| 32 | S7-1500 | CPU 1511C-1 PN | 6ES7511-1CK01-0AB0 | Compact CPU | Compact medium machines |
| 33 | S7-1500 | SM 521 DI 16x24VDC HF | 6ES7521-1BH00-0AB0 | Digital input module | Fast digital input acquisition |
| 34 | S7-1500 | SM 521 DI 32x24VDC HF | 6ES7521-1BL00-0AB0 | Digital input module | High-density digital inputs |
| 35 | S7-1500 | SM 522 DQ 16x24VDC/0.5A ST | 6ES7522-1BH01-0AB0 | Digital output module | Standard actuator outputs |
| 36 | S7-1500 | SM 522 DQ 32x24VDC/0.5A HF | 6ES7522-1BL01-0AB0 | Digital output module | High-density actuator outputs |
| 37 | S7-1500 | SM 531 AI 8xU/I/RTD/TC ST | 6ES7531-7KF00-0AB0 | Analog input module | Process and temperature signals |
| 38 | S7-1500 | SM 532 AQ 8xU/I HS | 6ES7532-5HF00-0AB0 | Analog output module | Precision analog control |
| 39 | S7-1500 | SM 534 AI/AQ | 6ES7534-7QE00-0AB0 | Mixed analog module | Compact process measurement and control |
| 40 | ET 200SP | DI 8x24VDC ST | 6ES7131-6BF01-0BA0 | Distributed input module | Remote digital inputs |
| 41 | ET 200SP | DQ 8x24VDC/0.5A ST | 6ES7132-6BF01-0BA0 | Distributed output module | Remote digital outputs |
| 42 | ET 200SP | AI 4xI 2-/4-wire ST | 6ES7134-6GD01-0BA1 | Distributed analog input | Remote process measurement |
| 43 | ET 200SP | AQ 4xU/I ST | 6ES7135-6HD00-0BA1 | Distributed analog output | Remote analog control |
| 44 | S7-1500 | CP 1543-1 | 6GK7543-1AX00-0XE0 | Communication processor | SCADA and industrial Ethernet |
| 45 | S7-1500 | CM PtP | 6ES7540-1AB00-0AA0 | Point-to-point module | Serial instruments and barcode readers |
| 46 | S7-1500 | TM Count 2 | 6ES7550-1AA00-0AB0 | Technology module | Encoders and high-speed counting |
| 47 | S7-1500 | TM PosInput 2 | 6ES7551-1AB00-0AB0 | Technology module | Position input and encoders |
| 48 | S7-1500 | PS 25W / PS 60W | 6ES7505-0KA00-0AB0 | System power supply | S7-1500 rack power |
| 49 | S7-1500 | PM 70W / PM 190W | 6EP1332-4BA00 | Load power module | Load and I/O power |
| 50 | ET 200MP | IM 155-5 PN ST | 6ES7155-5AA01-0AB0 | PROFINET interface module | Distributed ET 200MP I/O |
Model names are shown for planning and content discovery. A complete order number may vary by electrical variant, safety class, communication interface, hardware generation, and regional availability.