SCHMERSAL SRB-NA-R-C.35/CH2A-24V Safety Relay Controller | Replacement, Equivalent & Selection Guide
The SCHMERSAL SRB-NA-R-C.35/CH2A-24V is a dual-channel safety relay module designed for monitoring emergency stop buttons, safety gates, and light curtains in industrial automation systems. This page provides full technical specifications, compatible replacement models, application guidance, and a structured selection guide to help engineers and procurement teams make confident sourcing decisions.
Technical Specifications
- Manufacturer: SCHMERSAL
- Part Number: SRB-NA-R-C.35/CH2A-24V
- Supply Voltage: 24V DC
- Safety Category: Category 4 / PLe (EN ISO 13849-1)
- Safety Integrity Level: SIL 3 (IEC 62061)
- Input Channels: Dual-channel (CH2A)
- Output Contacts: 3 NO safety outputs + 1 NC auxiliary
- Response Time: ≤ 20 ms
- Operating Temperature: -25°C to +55°C
- Housing: 35 mm DIN rail mount
- Weight: 1,150 g
- Protection Class: IP40 (panel-mounted)
- Standards: EN 60947-5-1, EN ISO 13849-1, IEC 62061
Compatible Replacement & Equivalent Models
The following models are functionally equivalent or drop-in compatible replacements for the SRB-NA-R-C.35/CH2A-24V. Always verify wiring diagrams and output contact ratings before substitution.
- SCHMERSAL SRB-NA-R-C.35/CH2A-24V DC — Direct variant with DC-specific input filtering
- PILZ PNOZ X3 24VDC — Industry-standard equivalent; 3 NO + 1 NC, Cat. 4 / PLe
- PILZ PNOZ X3P 24VDC — Enhanced version with plug-in terminals
- SICK UE10-3OS2D0 — Compact equivalent for E-stop and gate monitoring
- OMRON G9SA-321-T075 24VDC — Modular safety relay with equivalent output configuration
- BANNER SI-RF2B — Two-hand control and E-stop compatible alternative
- TURCK MSI-SR4-01 — DIN rail safety relay with comparable SIL 3 rating
Note: Cross-reference verification is the responsibility of the end user. Contact Konmask.com for application-specific compatibility confirmation.
Why Choose the Original Model
- OEM Certification: Factory-certified to EN ISO 13849-1 Cat. 4 / PLe and SIL 3 — no re-validation required for existing machine safety assessments.
- Proven Field Reliability: Widely deployed in European and Asian manufacturing lines with documented MTBF data.
- Regulatory Compliance: Meets CE, UL, and cUL marking requirements out of the box.
- Exact Fit: 35 mm DIN rail footprint and terminal layout match existing panel designs — zero re-wiring for like-for-like replacement.
- Manufacturer Support: Full SCHMERSAL documentation, firmware, and technical support available.
Typical Applications
- Emergency stop (E-stop) circuit monitoring on industrial machinery
- Safety gate and interlocked guard door monitoring
- Light curtain and safety mat interface
- Two-hand control station safety circuits
- Robot cell perimeter guarding
- Press brake and stamping machine safety loops
- Conveyor and material handling safety interlocks
System Compatibility
- PLC Integration: Compatible with Siemens S7-300/400/1200/1500, Allen-Bradley CompactLogix/ControlLogix, Mitsubishi MELSEC, and Omron NX/NJ series via hardwired safety I/O.
- Safety Bus: Can be integrated into AS-Interface Safety at Work (ASIsafe) networks with appropriate gateway modules.
- Power Supply: 24V DC PELV power supply required (e.g., PHOENIX CONTACT QUINT, SIEMENS SITOP).
- Panel Standards: Compatible with IEC 60204-1 compliant control panel designs.
Selection Guide
Use the criteria below to confirm the SRB-NA-R-C.35/CH2A-24V is the correct module for your application, or to identify the most suitable alternative:
- Required Safety Level: If your risk assessment demands Cat. 4 / PLe or SIL 3, this module qualifies. For lower-risk applications (Cat. 2 / PLc), consider the SRB-NA-R-C.20 series.
- Input Channel Configuration: CH2A = dual-channel monitored input. For single-channel applications, select the CH1A variant.
- Supply Voltage: This model is 24V DC only. For 24V AC/DC or 110/230V AC applications, select the appropriate SRB-NA-R-C.35 voltage variant.
- Output Contact Count: 3 NO safety + 1 NC auxiliary. If more outputs are required, consider the SRB-NA-R-C.35/CH2A-24V with expansion modules or the PILZ PNOZ m B0 modular system.
- Restart Mode: Manual monitored restart (default). Automatic restart variants available — specify at order.
- Mounting: 35 mm DIN rail standard. Confirm panel depth ≥ 60 mm for proper installation.
Quality Assurance & Sourcing
- Authenticity: All units sourced by Konmask.com are procured through verified industrial distribution channels. Certificates of conformity available on request.
- Inspection: Each unit undergoes visual and functional pre-shipment inspection.
- Packaging: Ships in original OEM packaging with full documentation where available.
- Traceability: Batch and serial number records maintained for B2B compliance requirements.
- Warranty: 12-month warranty against manufacturing defects. Extended warranty available for volume orders.
How to Order
- Online: Add to cart directly on this page. Bulk pricing available for orders of 5+ units — contact us for a quote.
- Email: Send your BOM or part number list to support@konmask.com
- Phone/WhatsApp: +0086 19859288691 (Mon–Fri, 09:00–18:00 CST)
- Lead Time: In-stock units ship within 1–3 business days. Ex-stock orders confirmed at time of inquiry.
- Payment: T/T bank transfer, PayPal, and major credit cards accepted. Net-30 terms available for approved accounts.
Replacement & Compatibility FAQ
Q: Can I replace the SRB-NA-R-C.35/CH2A-24V with a PILZ PNOZ X3 without re-validating my safety assessment?
A: In most cases, yes — both are Cat. 4 / PLe and SIL 3 rated with identical output configurations. However, your local machinery safety engineer should confirm based on your specific risk assessment documentation.
Q: Is this module suitable for ATEX / hazardous area installations?
A: The standard SRB-NA-R-C.35/CH2A-24V is rated IP40 and is not ATEX certified. For hazardous area applications, contact Konmask.com for ATEX-rated alternatives.
Q: What is the difference between CH2A and CH2B input configurations?
A: CH2A uses a dual-channel input with cross-fault detection and manual monitored reset. CH2B adds an additional feedback loop monitoring circuit for actuator monitoring (e.g., contactors). Select CH2B when your safety circuit includes external contactors that must be monitored.
Q: Can I use this relay with a 24V AC supply?
A: No. This model is 24V DC only. For AC supply compatibility, select the SRB-NA-R-C.35/CH2A-24V AC variant or contact us for the correct part number.
Q: Do you provide a datasheet or wiring diagram?
A: Yes. Full SCHMERSAL technical documentation is available upon request. Email support@konmask.com with your order reference or inquiry number.
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Contact: support@konmask.com | +0086 19859288691
