New In-Box EUCHNER Safety Switch STP4A-4121A024M

EUCHNER · STP Series · Tongue-Actuated Safety Switch · New In Box

The STP4A-4121A024M is a tongue-actuated safety switch from EUCHNER's STP family, designed for monitoring the position of movable safety guards — hinged doors, sliding gates and protective covers on industrial machinery. The 4121 contact arrangement delivers one normally-open and one normally-closed contact, the 024 suffix indicates a 24 V AC/DC solenoid supply, and the M12 connector on the housing makes field replacement a one-handed, tool-light operation. KOEED supplies the STP4A-4121A024M as new, factory-sealed EUCHNER inventory — the same safety component that machine builders and OEM panels specify on nameplates inside their bills of materials. KOEED's audited multi-brand supply chain covers Allen-Bradley, Siemens, Mitsubishi, Omron, Fanuc, Schneider, Yaskawa, Panasonic and KEYENCE for PLC, servo, HMI, CNC and robotics — and extends into the safety component brands that guard interlock designers actually deploy in Cat 3 / PL d circuits. EUCHNER is widely recognized as one of the German reference brands for guard interlock switches, with the STP family being the workhorse choice for non-coded, mechanically-tamper-evident interlock applications.

For safety engineers and panel builders, the STP4A is a fit-and-forget component: positive-opening NC contact, IP67 enclosure, four-pin M12 connector, and a thermoplastic body that tolerates outdoor and washdown environments. When wired to a Cat 3 or Cat 4 safety relay — Pilz PNOZ s5/s4, Sick FX3-XTIO, Allen-Bradley MSR127RP or Siemens 3SK1111 — the resulting circuit meets PL d per ISO 13849-1 and SIL 2 per IEC 62061. KOEED keeps the STP4A-4121A024M in active stock for OEM and retrofit buyers, with worldwide shipping dispatched within 24 hours of payment confirmation and traceability documents attached to every shipment. Bulk-pricing tiers are available for machine builders integrating the switch across a full product line, and full BOM quotes can be assembled across switches, actuators, safety relays and pre-wired M12 cords in one consolidated shipment.

The part-number convention reads cleanly: STP for the tongue-actuated series, 4A for the four-pin M12 A-coded connector, 4121 for the 1 NO + 1 NC contact arrangement, A for housing keying, 024 for 24 V AC/DC operation and M for the metric thread variant. Knowing the convention makes it easier to cross-reference the STP4A-4121A024M against an OEM datasheet, or to identify a near-equivalent (STP3A, STP-BI, CTP-BP) when lead times shift.

Key Specifications

Datasheet Highlights

Engineers building a safety circuit around the STP4A-4121A024M should pay attention to the following datasheet details before selecting the matching relay and actuator:

• 1 NO + 1 NC positively-driven contact set — the NC contact opens by positive mechanical force when the actuator is withdrawn, satisfying IEC 60947-5-1 Annex K and ISO 14119 guard-interlock requirements. This is the spec most safety inspectors check first.
• M12 A-coded 4-pin connector — field replacement requires no rewiring, no soldering and no special tooling. A standard M12 patch cord (open-wire or pre-wired) plugs straight into the switch body, cutting MTTR during a line stop and letting the same cord stock fit PLC I/O and safety I/O blocks.
• IP67 enclosure rating — tolerates jet-wash and temporary immersion to 1 m for 30 minutes, suitable for food & beverage, pharmaceutical, dairy and outdoor washdown cells where a die-cast switch would pit or corrode.
• H-bridge compatible actuator — accepts EUCHNER actuator variants (bent, straight, short, long) so the same switch body can be mounted on hinged, sliding or removable guards without re-engineering the bracket or re-drilling the door frame.
• Thermoplastic housing — lighter and corrosion-free compared to die-cast alternatives, ideal for OEMs shipping into multi-region marine and chemical environments where salt or solvent exposure would attack a metal body.
• Positive-break force on NC contact — meets the 10 N minimum opening force required by EN ISO 14119, even after wear or vibration-induced misalignment of the actuator. This is the property that prevents a stuck or bent actuator from leaving the safety circuit falsely closed.
• B10d and MTTFd values published in the EUCHNER datasheet — can be entered directly into SISTEMA, PAScal or the IFA safety calculator for PL d / PL e proof, saving safety-engineer review time at the design stage and producing audit-ready documentation.
• Compatible with EUCHNER's own M12 connection cords and Y-distributors — meaning a single 4-pin cord carries both safety contacts back to the safety relay without extra marshalling, and a Y-distributor can branch the safety loop to a second door on the same cell.

Typical Applications

The STP4A-4121A024M is most often specified on safety guard doors where a non-coded mechanical interlock is acceptable and a positive-break NC contact is mandatory. Typical deployments include:

• Safety guard interlocking on CNC machining centers, lathes and milling cells
• Hinged and sliding door monitoring on automotive body-in-white and final assembly stations
• Robotic work-envelope gates and perimeter fence doors (in combination with safety relays)
• Packaging machinery, palletizer doors and case-packer access panels
• Food & beverage washdown conveyors and dairy / brewery process skids (IP67 benefit)
• Pharmaceutical and cosmetics filling lines where frequent washdown is required
• Press tools, stamping, forming and shearing machines under ISO 13849-1 / IEC 62061
• Retrofit of worn-out OEM safety switches on legacy Logix / SIMATIC / TIA Portal cells
• Semi-conductor front-end equipment and battery cell assembly cells

Related Modules & Cross-Reference

Warranty & Authenticity

Each STP4A-4121A024M ships as a new, factory-sealed EUCHNER part sourced through KOEED's audited multi-brand supply chain. We do not sell pulled, relabeled, or refurbished units — every shipment is traceable to the original EUCHNER carton and date code, and a 12-month replacement warranty applies to manufacturing defects. Worldwide shipping is dispatched from KOEED's Shenzhen and Hong Kong logistics bases within 24 hours of payment confirmation, with full traceability documents (commercial invoice, packing list, EUCHNER origin paperwork) accompanying every order. For warranty claims, RMA requests, or to ask for a Certificate of Origin and date-code confirmation before shipment, contact Moritta@KOEED.COM and reference the order line item.

For machine builders sourcing in volume, KOEED supports bulk BOM quotation: send a full safety-circuit BOM — switches, actuators, safety relays, pre-wired M12 connection cords — and we will quote the lot at once, with one consolidated invoice and one shipment. Bulk-pricing tiers apply once a per-line threshold is met, and the same SKU is held against a reserved stock pool for frame-contract customers who need a predictable lead time on safety components.

KOEED is not an authorized EUCHNER distributor and does not represent the manufacturer; every unit is sourced through KOEED's audited secondary channels to keep the EUCHNER genuine, sealed and traceable. This is the KOEED difference: the multi-brand PLC, servo, HMI and safety supply chain that consolidates the bill of materials for OEM, system-integrator and retrofit buyers across the Allen-Bradley, Siemens, Mitsubishi, Omron, Fanuc, Schneider, Yaskawa, Panasonic and KEYENCE ecosystems — and the safety components that bolt onto those machines.