Siemens 6ES7403-1TA01-0AA0 System-Ready CR2 Rack for S7-400 Architecture

Siemens 6ES7403-1TA01-0AA0 System-Ready CR2 Rack for S7-400 Architecture

The Siemens 6ES7403-1TA01-0AA0 is an 18-slot CR2 Central Rack engineered as the structural and electrical backbone of the SIMATIC S7-400 control system architecture. Unlike peripheral expansion racks, the CR2 serves as the primary integration point where the CPU, power supply, communication processors, and I/O modules converge into a unified, high-availability control platform. In large-scale industrial automation environments — from petrochemical process plants to steel rolling mills and power distribution substations — the mechanical and electrical integrity of the central rack directly determines the reliability of the entire control loop. The 6ES7403-1TA01-0AA0 is designed to meet these demands with a robust aluminum profile structure, integrated backplane bus, and full compatibility with the S7-400 module ecosystem.

Deploying this rack within a layered automation architecture means every upstream and downstream system component — from field-level sensors to SCADA supervisory layers — depends on the rack’s bus integrity and slot allocation for deterministic signal flow. Engineers specifying this rack for new installations or system expansions benefit from its proven compatibility with the full range of S7-400 CPUs, power supply units, and communication modules, ensuring long-term architectural consistency and reduced integration risk.

Architecture Specification Table

Coordinated Control System Design

The 6ES7403-1TA01-0AA0 CR2 rack is the physical and logical center of a coordinated S7-400 control system. Its 18 slots accommodate the full range of modules required for a complete automation solution, and its design supports both standalone and redundant system configurations.

At the processing layer, the rack hosts high-performance CPUs such as the 6ES7414-3XM05-0AB0 (CPU 414-3 PN/DP) or the 6ES7416-3XR05-0AB0 (CPU 416-3 PN/DP), which provide the computational backbone for complex process control, motion sequencing, and real-time data acquisition. These CPUs communicate directly with the backplane bus, ensuring deterministic cycle times across all installed I/O modules.

Power integrity is maintained through dedicated PSU modules such as the 6ES7407-0DA02-0AA0 (PS 407 4A) or the 6ES7407-0KA02-0AA0 (PS 407 10A), which occupy the leftmost slot of the CR2 rack and supply regulated 5 VDC and 24 VDC to all installed modules via the backplane. In high-availability applications, dual PSU configurations with load-sharing capability can be implemented within the same rack, eliminating single points of failure at the power layer.

For distributed I/O integration, the rack supports analog and digital I/O modules including the 6ES7431-1KF20-0AB0 (SM 431 Analog Input) and 6ES7422-1BL00-0AA0 (SM 422 Digital Output), which connect directly to field instrumentation, actuators, and drive systems. Signal conditioning, scaling, and diagnostics are handled at the module level, reducing CPU load and simplifying commissioning.

Network connectivity is achieved through communication processor modules such as the 6GK7443-1EX30-0XE0 (CP 443-1 PROFINET) or the 6GK7443-5DX05-0XE0 (CP 443-5 PROFIBUS DP), which enable the S7-400 system to participate in plant-wide PROFINET or PROFIBUS networks, connecting to remote I/O stations, variable frequency drives, and intelligent field devices. These CP modules are installed directly into the CR2 rack slots, maintaining a compact and organized control cabinet layout.

For systems requiring expansion beyond the 18 slots of the CR2 rack, expansion racks such as the 6ES7400-1TA01-0AA0 (ER1 Expansion Rack) can be connected via interface modules, extending the I/O capacity while maintaining a single logical system under the central CPU. This architecture supports modular growth without requiring system redesign or CPU replacement.

In redundant system designs, the CR2 rack can be paired with a second rack hosting a standby CPU module, with synchronization handled through fiber-optic or copper sync cables. This H-system redundancy architecture, common in power generation and chemical processing applications, ensures seamless failover with no process interruption.

Application in Layered Automation Systems

The 6ES7403-1TA01-0AA0 CR2 rack is deployed across a wide range of industrial sectors where system reliability, scalability, and long-term maintainability are non-negotiable requirements.

In power generation and distribution facilities, the S7-400 system built around this rack manages turbine control, transformer protection relay coordination, and substation automation. The rack’s ability to host redundant CPUs and dual power supplies makes it the preferred choice for applications where unplanned downtime carries significant financial and safety consequences.

In petrochemical and refinery environments, the CR2 rack serves as the central controller for distillation column management, compressor sequencing, and emergency shutdown system (ESD) integration. Its compatibility with HART-enabled analog input modules and PROFIBUS PA field devices ensures seamless integration with process instrumentation at all levels of the ISA-95 automation hierarchy.

In steel and metallurgical plants, the rack hosts CPUs responsible for rolling mill speed synchronization, furnace temperature profiling, and cooling water flow control. The high slot count of the CR2 rack allows engineers to consolidate multiple control functions within a single rack, reducing cabinet footprint and simplifying inter-system wiring.

In water and wastewater treatment facilities, the S7-400 system centered on this rack manages pump station sequencing, chemical dosing control, and SCADA data aggregation. The rack’s long product lifecycle and Siemens’ commitment to spare parts availability ensure that water utilities can maintain system continuity over multi-decade operational horizons.

In automotive and discrete manufacturing assembly lines, the CR2 rack coordinates robot cell controllers, conveyor drive systems, and quality inspection stations through high-speed digital I/O modules and PROFINET communication, supporting cycle times measured in milliseconds.

Architecture Engineering FAQ

Q1: Is the 6ES7403-1TA01-0AA0 compatible with all S7-400 CPU and I/O modules?
Yes. The CR2 rack is fully compatible with the complete SIMATIC S7-400 module range, including all CPU 41x series processors, PS 407 power supply modules, SM 4xx signal modules, CP 44x communication processors, and FM 45x function modules. The integrated P-bus and K-bus backplane ensures electrical and mechanical compatibility across the entire S7-400 product family. When planning slot assignments, always refer to the S7-400 system manual (A5E00850745) to observe CPU-specific slot restrictions and power budget calculations.

Q2: Can this rack be used in an H-system (redundant) S7-400 configuration, and what additional components are required?
Yes. The 6ES7403-1TA01-0AA0 CR2 rack supports H-system redundancy when paired with a compatible redundant CPU (e.g., CPU 414H or CPU 417H) and the corresponding sync module. Two CR2 racks are required — one for the active CPU and one for the standby CPU — connected via fiber-optic or copper synchronization cables. The redundancy coordinator module manages automatic switchover in the event of a CPU fault, power failure, or communication error, with switchover times typically under 100 ms. This configuration is fully supported by STEP 7 and TIA Portal engineering environments.

Q3: What does the 12-Month Warranty cover, and how is long-term spare parts availability managed for this rack?
The 12-Month Warranty covers manufacturing defects, backplane bus failures, and mechanical integrity issues under normal operating conditions. Warranty claims are processed through ZYPLC’s technical support team, with replacement units dispatched within agreed lead times. For long-term maintenance planning, the 6ES7403-1TA01-0AA0 remains an active catalog item with confirmed spare parts availability. ZYPLC maintains buffer stock of this rack to support emergency replacement requirements, minimizing unplanned downtime for installed base customers. For multi-year maintenance contracts or volume procurement, contact our engineering sales team directly.

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