Product Overview

The Siemens 435-CPU​ is the central processing unit for the SIMATIC TDC (Technology and Drive Control) system, representing the pinnacle of Siemens’ programmable logic controller (PLC) technology for ultra-high-performance, deterministic control applications. It functions as a powerful, multi-processor control computer engineered for tasks requiring extremely fast processing speeds, precise synchronization, and complex algorithm execution, such as those found in rolling mill drives, paper machines, test benches, and printing presses. Unlike standard PLCs, the Siemens 435-CPU​ is designed around a parallel, multi-computing architecture where multiple internal processor boards work in concert, enabling it to handle thousands of I/O points and execute complex function blocks in cycle times as low as 100 microseconds. This system is the core orchestrator for coordinating multiple drives, hydraulic axes, and high-speed measurement systems with nanosecond-level synchronization.As the heart of the SIMATIC TDC rack, the Siemens 435-CPU​ is responsible for executing the user-programmed control strategy, which is typically written in high-level languages like CFC (Continuous Function Chart) or structured text within the Siemens Engineering System. It manages the entire backplane communication, processes data from local and remote I/O modules, performs high-speed calculations for control loops, and handles peer-to-peer communication with other TDC CPUs for distributed control architectures. The value of the Siemens 435-CPU​ lies in its ability to perform deterministic control of highly dynamic processes that are beyond the capability of conventional PLCs. It bridges the gap between classic automation and drive technology, providing a unified platform for implementing sophisticated technology functions like cross-directional control, tension control, and complex multi-axis coordination, all while seamlessly integrating into the larger SIMATIC PCS 7 or TIA Portal ecosystem for visualization and higher-level supervision.

Technical Specifications

Main Features and Advantages

The Siemens 435-CPU​ is distinguished by its unparalleled processing power and parallel computing architecture. This design allows it to execute numerous complex control tasks—such as hundreds of PID controllers, complex mathematical models, and coordination algorithms—simultaneously within a single, ultra-short cycle. This determinism is critical for applications like metal rolling, where the coordination of multiple stand drives must be perfectly synchronized to prevent strip tearing or buckling. The Siemens 435-CPU​ provides specialized technology function blocks (TBs) optimized for drive and motion control, enabling engineers to implement advanced control strategies with drag-and-drop simplicity in the CFC editor, significantly reducing engineering time for complex applications.High-speed communication and system scalability are core advantages. The CPU manages the Gigabit Backplane Bus (GDM) for ultra-fast data exchange with I/O and communication modules within the same rack. For multi-CPU systems, it utilizes high-speed fiber-optic links (like SINEC H2) for low-latency peer-to-peer communication, enabling the construction of distributed control systems that behave like a single, cohesive unit. The Siemens 435-CPU​ also supports seamless integration with Siemens drives via DRIVE-CLiQ and with higher-level systems via Industrial Ethernet (PROFINET/ETHERNET). Furthermore, it offers extensive diagnostic and monitoring functions, providing deep insight into the system’s performance and health. Its modular and scalable nature, centered on the powerful 435-CPU, allows systems to be tailored precisely to the application’s demands, from a single-cabinet solution to a plant-wide, multi-rack automation network, ensuring both maximum performance and long-term investment security.