In the world of industrial automation, choosing the right controller is the foundation of a successful project. For engineers working with the Siemens ecosystem, the choice often comes down to two heavyweights: the compact SIMATIC S7-1200 and the high-performance SIMATIC S7-1500.
While both PLCs share the same engineering framework via the TIA Portal, they serve very different purposes.
In this guide, we will break down the critical differences in performance, scalability, and cost to help you make the right decision.
1. The Contenders: A Brief Overview
Before we dive into the technical specs, let’s define the role of each controller.
- Siemens S7-1200: Known as the “Basic Controller,” the S7-1200 is designed for compact automation solutions. It is cost-effective, flexible, and perfect for standalone machines or simple networked applications.
- Siemens S7-1500: Known as the “Advanced Controller,” this is the successor to the legendary S7-300 and S7-400. It is built for medium to high-end machine and plant automation, offering superior system performance and advanced motion control.
2. Performance and Processing Speed
When it comes to Siemens PLC programming, processing speed is often the deciding factor.
The S7-1500 is significantly faster. It boasts a backplane bus speed that ensures extremely short reaction times, making it ideal for high-speed packaging machines or complex production lines. The bit execution time in an S7-1500 can be as low as 1ns (nanosecond), whereas the S7-1200 operates in the nanosecond to microsecond range depending on the CPU model.
Winner: S7-1500 (for high-speed applications).
3. Comparison Table: S7-1200 vs. S7-1500
For a quick technical reference, here is a side-by-side comparison:
| Feature | SIMATIC S7-1200 | SIMATIC S7-1500 |
| Target Application | Basic / Compact Machines | Medium / High-End Plant Automation |
| Processing Speed | Medium | Very High |
| Display | No on-board display | Built-in Color Display (for diagnostics) |
| Motion Control | Basic (Speed/Positioning) | Advanced (Gearing, Camming, Kinematics) |
| Expandability | Limited local I/O modules | Extensive local & distributed I/O |
| PROFINET | 1 Interface (typically) | Up to 3 Interfaces (varies by CPU) |
| Engineering Software | TIA Portal Basic / Professional | TIA Portal Professional |
| Price Range | $ Low – Mid | $$$ Mid – High |
(Need a quote for these modules? Check our S7-1200 Inventory here or View S7-1500 Prices here.)
4. Display and Diagnostics
One of the most visible differences is the hardware design.
The S7-1500 features a built-in color display on the CPU faceplate. This allows engineers to check IP addresses, view error codes, and perform diagnostics without connecting a laptop. This feature drastically reduces downtime during troubleshooting.
The S7-1200 relies on LEDs for status indication. To view detailed diagnostics, you must connect via TIA Portal or use an external HMI panel.
5. Scalability and Motion Control
If your project involves complex motion control—such as synchronizing multiple axes, camming, or operating kinematics—the S7-1500 is the clear choice. It handles advanced motion control tasks natively without needing specialized add-on modules.
However, for standard tasks like simple positioning or speed control of a conveyor belt, the S7-1200 is more than capable and much more budget-friendly.
6. Conclusion: Which One Should You Buy?
Choose the Siemens S7-1200 if:
- You are building a standalone machine with limited I/O.
- Budget is a primary concern.
- You only need basic motion control and networking.
- Shop S7-1200 CPUs
Choose the Siemens S7-1500 if:
- You are automating a large production line or complex plant.
- You require high-speed processing and fast reaction times.
- You need advanced diagnostics via the on-board display.
- You are migrating from older S7-300/400 systems.
- Shop S7-1500 CPUs
At Turll, we specialize in supplying 100% new and original Siemens automation parts. Whether you need the compact 1200 or the powerful 1500, we have thousands of units in stock ready for global shipping.
Need help selecting the right CPU? Contact our engineering team today for a free consultation.