SIEMENS 6ES7924-0CC20-0AA0 – 40-Pin Front Connector for Field Wiring | SIMATIC S7-300 Platform
Engineering Background: In SIMATIC S7-300 distributed control architectures, the front connector is the critical interface between the PLC signal module and the field instrumentation. The 6ES7924-0CC20-0AA0 is Siemens’ 40-pin screw-type front connector, engineered specifically for S7-300 signal modules with 40-pin interfaces (SM 321, SM 322, SM 331, SM 332 series). It enables clean, maintainable field wiring that can be disconnected from the module without disturbing the cable harness — a fundamental requirement in industrial maintenance workflows.
Product Positioning: This connector is a mandatory BOM component for any S7-300 I/O module deployment. It is not a peripheral accessory — without it, the signal module cannot interface with field devices. Procurement engineers specifying S7-300 expansions must include one 6ES7924-0CC20-0AA0 per 40-pin SM module in their bill of materials.
Complete Technical Specifications
- Part Number: 6ES7924-0CC20-0AA0
- Product Family: SIMATIC S7-300 Front Connectors
- Connection Type: Screw-type terminals (0CC20 = screw terminal variant)
- Pin Count: 40-pin (for 40-pin S7-300 signal modules)
- Compatible Modules: SM 321, SM 322, SM 331, SM 332 (40-pin variants)
- Conductor Cross-Section: 0.25 – 1.5 mm² (solid or stranded)
- Rated Voltage: Up to 250 V AC/DC
- Rated Current per Contact: 10 A max
- Degree of Protection: IP20 (when installed)
- Operating Temperature: 0 °C to +60 °C
- Storage Temperature: –40 °C to +70 °C
- Mounting: Snap-on to S7-300 signal module front face
- Labeling: Integrated label strip holder for field identification
- Dimensions (W × H × D): Approx. 40 × 130 × 50 mm
- Weight: Approx. 80 g
- Color: Light gray (RAL 7035)
- MLFB / Order Number: 6ES7924-0CC20-0AA0
- Siemens Product Group: 6ES7924
- RoHS Compliant: Yes
- Country of Origin: Germany
Proven Application Environments
- Automotive Manufacturing: Body-in-white welding lines, paint shop conveyors, and final assembly stations using S7-300 PLCs with dense I/O configurations require reliable front connectors for sensor/actuator termination.
- Chemical & Petrochemical Plants: Process control panels where S7-300 SM 331 analog input modules monitor temperature, pressure, and flow — each requiring a 40-pin front connector for transmitter wiring.
- Water & Wastewater Treatment: SCADA-integrated S7-300 systems controlling pump stations and dosing systems rely on front connectors for field cable management and module swap-out during maintenance windows.
- Food & Beverage Processing: Hygienic production lines with frequent cleaning cycles benefit from the snap-off connector design, allowing module replacement without rewiring.
- Building Automation & HVAC: Central BMS panels using S7-300 for multi-zone climate control, where I/O density demands 40-pin modules and organized field termination.
- Machine Tool & CNC: Machining centers with S7-300 controlling servo drives, spindle motors, and safety interlocks — front connectors provide the structured wiring interface for high-channel-count I/O.
Engineering Advantages
- Module-Independent Wiring: Field cables remain connected to the front connector during module replacement — zero rewiring time during maintenance, critical for minimizing production downtime.
- Screw Terminal Reliability: Screw-type termination (vs. spring-cage) provides vibration-resistant, gas-tight connections suitable for industrial environments with mechanical stress.
- Integrated Labeling System: Built-in label strip holder accepts standard Siemens labeling strips for clear, permanent field identification of each terminal point.
- Keying Mechanism: First-time installation sets a mechanical key that prevents incorrect module type from being inserted — eliminates wiring errors during module swaps.
- High Current Capacity: 10 A per contact supports direct connection of actuators and solenoid valves without intermediate terminal blocks in many applications.
- Compact Form Factor: Designed to fit within standard S7-300 rack spacing — no additional panel space required beyond the module footprint.
System Architecture & Signal Flow
In a typical S7-300 control cabinet, the signal flow is: Field Device → Cable Harness → 6ES7924-0CC20-0AA0 Front Connector → S7-300 Signal Module (SM 321/322/331/332) → S7-300 Backplane Bus → CPU (e.g., 6ES7315-2EH14-0AB0) → PROFIBUS/MPI/Ethernet → SCADA/HMI.
The front connector is the first point of signal entry into the PLC system. Proper termination at this stage — correct conductor sizing, torque specification (0.8–1.1 Nm for screw terminals), and shield grounding — directly determines signal integrity for the entire control loop. Engineers should reference Siemens Manual 6ES7924-0CC20-0AA0 Installation Guide and the relevant SM module hardware manual for terminal assignment diagrams.
Sourcing & Quality Verification
- Authenticity: All units sourced by Konmask.com are verified against Siemens’ product identification standards, including holographic labels, MLFB code validation, and physical inspection against OEM specifications.
- Traceability: Batch traceability documentation available upon request for quality-critical procurement (ISO 9001 / IATF 16949 supply chains).
- Condition: New (factory-sealed) and tested surplus stock available — condition clearly stated per order.
- Lead Time: In-stock units ship within 1–3 business days. Contact us for volume availability and expedited options.
- Warranty: 12-month warranty against manufacturing defects on all units supplied by Konmask.com.
Procurement Process
- Confirm your S7-300 signal module part number and verify it uses the 40-pin interface (check Siemens catalog or module label).
- Determine quantity: one 6ES7924-0CC20-0AA0 required per 40-pin SM module.
- Submit RFQ via Konmask.com product page or email support@konmask.com with quantity and delivery requirements.
- Receive quotation with lead time, unit price, and shipping options within 24 business hours.
- Confirm PO — payment via T/T, PayPal, or trade terms for qualified accounts.
- Shipment with tracking, commercial invoice, and packing list. Customs documentation available for international orders.
Technical FAQ
- Q: What is the difference between 6ES7924-0CC20-0AA0 and 6ES7924-0CA20-0AA0?
- A: The 0CC20 variant is the 40-pin screw-type front connector. The 0CA20 is the 20-pin screw-type variant for smaller S7-300 modules. Always match the pin count to your signal module specification.
- Q: Can I use this connector with S7-400 or S7-1500 modules?
- A: No. The 6ES7924-0CC20-0AA0 is exclusively designed for SIMATIC S7-300 signal modules. S7-400 and S7-1500 use different connector systems.
- Q: What wire gauge is recommended for analog signal wiring?
- A: For analog signals (4–20 mA, 0–10 V), use shielded twisted-pair cable, 0.5 mm² (AWG 20) minimum. Connect shield to the module’s shield terminal, not to the front connector terminal.
- Q: Is the keying mechanism pre-set or field-configurable?
- A: The key is set automatically on first insertion into a specific module type. Subsequent insertions are mechanically restricted to the same module type — this is a safety feature, not a limitation.
- Q: Can I order with a certificate of conformity?
- A: Yes. Konmask.com provides CoC documentation upon request. Contact support@konmask.com with your PO details.
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