Siemens Sinumerik 840D SL NCU 720.3B with PLC 317-3 PN/DP

Product Overview

The Siemens Sinumerik 840D SL NCU 720.3B PN (order number 6FC5372-0AA30-0AB0) is a high-performance Numerical Control Unit for the Sinumerik 840D sl platform. This unit integrates CNC control, PLC functionality, and industrial communication interfaces into a single compact module. The NCU 720.3B is engineered to manage multi-axis machining processes, providing precise motion control for complex operations in aerospace, automotive, and precision engineering industries.

Technical Specifications

Processor and Memory

The NCU 720.3B is equipped with an Intel Core 2 T7400 processor operating at 2.1 GHz. The unit features 3 MB of dedicated NC memory and 1 GB of DRAM for system functions. Non-volatile memory is provided at 1 MB for persistent data storage. The dedicated memory allocation ensures deterministic performance even in demanding production environments.

Integrated PLC

The NCU incorporates an integrated S7-300 PLC 317-3 PN/DP with 512 KB of memory. This integrated PLC enables automation and process control logic without requiring additional hardware. The PLC supports both PROFINET and PROFIBUS DP communication protocols, providing flexible connectivity for field devices and I/O systems.

Communication Interfaces

The NCU 720.3B supports flexible industrial communication through PROFINET and PROFIBUS DP interfaces. These communication protocols enable seamless integration into existing industrial networks and support connection to a wide range of Siemens and third-party devices. The unit functions as a CNC control system, PLC integration platform, and communication gateway within the Sinumerik 840D sl environment.

Physical Characteristics

The NCU 720.3B includes a twin fan module that maintains optimal thermal performance for continuous operation. The net weight of the unit is 3.9 kg, and it is manufactured in Germany. The compact design allows for efficient use of control cabinet space while providing comprehensive CNC and PLC functionality.

Key Functions

The NCU 720.3B integrates CNC control, PLC integration, and communication gateway functions into a single unit. The CNC control provides precise motion control for complex multi-axis machining operations, supporting advanced interpolation algorithms and high-speed machining capabilities. The integrated S7-300 PLC enables machine logic control directly on the NCU, eliminating the need for separate PLC hardware. The PROFINET and PROFIBUS DP interfaces allow connection to operator panels, drives, I/O devices, and other field devices.

System Compatibility

The NCU 720.3B is designed for the Sinumerik 840D sl platform and is compatible with Siemens Sinamics drive systems. The unit supports CNC software version 31.3 and is optimized for multi-axis CNC machining applications in aerospace, automotive, and precision manufacturing industries.

Lifecycle Information

As of October 2023, this product has entered its phase-out stage and is available primarily as a spare part for existing installations. Siemens recommends newer NCU models such as NCU 720.5 or NCU 730.5 for modern installations, but spare parts and service remain accessible for legacy systems.