Siemens Sinumerik 840D sl NCU 710.2 Control Unit

The Siemens 6FC5371-0AA10-0AA1 is an NCU 710.2 (Numerical Control Unit) for the Sinumerik 840D sl CNC system. This high-performance controller integrates both numerical control (NC) and programmable logic controller (PLC) functions in a single unit. It includes an integrated PLC 317-2DP (SIMATIC S7-300) for machine logic and auxiliary functions. The NCU 710.2 supports up to 16 axes/spindles (with optional licenses) and up to 10 interpolated axes. It is designed for advanced machine tools such as milling machines, lathes, machining centers, and grinding machines. The unit is housed in a compact NCU box with fanless cooling and connects to drive systems via PROFIBUS or PROFINET.

Technical Specifications

Processor: 64-bit RISC, 266 MHz. NC memory: 2 MB (user memory). PLC memory: 512 KB (program and data). Number of axes: max 16 (with option). Number of interpolated axes: up to 10. Communication: PROFIBUS DP (12 Mbit/s) for drives and I/O, PROFINET for higher-level networks. Built-in interfaces: Ethernet (10/100 Mbps) for programming and HMI, USB 2.0. Supply voltage: 24 V DC (20.4-28.8 V), consumption 0.9 A. Dimensions: 300 mm × 48 mm × 208 mm (6U, single-width). Weight: 1.5 kg. Operating temperature: 0°C to 55°C. Storage: -20°C to 60°C. Protection: IP20. The unit includes a real-time clock with battery backup. The PLC is compatible with SIMATIC S7-300 instructions and can be programmed with STEP 7.

Key Features

• Integrated NC and PLC (PLC 317-2DP) for complete machine control

• Controls up to 16 axes/spindles (10 interpolated)

• PROFIBUS DP interface for SINAMICS drives and I/O

• Ethernet port for HMI and network communication

• Fanless design for low maintenance

• Compatible with Sinumerik 840D sl HMI (PCU 50.5)

• Supports advanced CNC functions: splines, 3D tool compensation, high-speed machining

• Certified for safety functions (SINUMERIK Safety Integrated)

Programming and Integration

The NC part is programmed in G-code (DIN 66025) using Sinumerik Operate or via external CAM systems. The PLC part is programmed using STEP 7 (TIA Portal or Classic). The NCU connects to SINAMICS S120 drives via PROFIBUS DP. It can also interface with digital I/O modules via PROFINET. The unit includes a built-in web server for diagnostics.

Applications

The NCU 710.2 is used in high-end CNC machine tools requiring complex contouring and high-speed machining. Typical applications include 5-axis milling centers, turn-mill centers, grinding machines, and heavy-duty lathes. It is suitable for aerospace, automotive, and general machining industries.

Installation

Mount the NCU in a 19-inch rack or cabinet using the supplied brackets. Connect 24V DC power to the connector. Connect PROFIBUS cable to the 9-pin D-sub (drive bus). Connect Ethernet to the HMI and plant network. I/O modules connect via PROFINET. Insert the CompactFlash card containing the NC software and license keys. The unit has no internal fan; ensure adequate cabinet ventilation.

Maintenance and Diagnostics

The NCU has LEDs for status: PWR (green), NC active (green), PLC active (green), error (red). If the red LED is lit, check the diagnostic buffer via the HMI. The real-time clock battery (CR2032) may need replacement every 3-5 years. The CompactFlash card is field-replaceable. No other user-serviceable parts.

Conclusion

The Siemens 6FC5371-0AA10-0AA1 NCU 710.2 is a powerful CNC controller for the Sinumerik 840D sl platform. Its integrated PLC and robust design make it a reliable choice for advanced machine tool applications requiring high precision and multi-axis control.