Simatic S7-400
SIMATIC S7-400 – High-Performance Automation by Siemens
The SIMATIC S7-400 is a modular PLC system from Siemens designed for mid to high-end performance levels. Introduced in 1998 as the successor to the SIMATIC S5-135/155, it is widely used in demanding industries such as the process industry, automotive sector, chemical plants, steel production, and process engineering.
The system includes:
- CPUs in various performance classes, with integrated I/Os and interfaces like PROFIBUS DP, PROFINET, and point-to-point communication
- Signal modules (SM) for digital and analog I/Os
- Communication processors (CP) for networking and serial connections
- Function modules (FM) for fast counting, positioning, and closed-loop control
For applications requiring high availability, the S7-400H offers a redundant system architecture. For safety-critical environments, the S7-400F/FH is the fail-safe version ensuring functional safety.
Programming is done via STEP 7 or the TIA Portal (version 11 or higher). The S7-400 has been continuously updated over the years while retaining its mechanical format – making it one of the most reliable PLCs in long-term industrial use.