The KEYENCE GS-51P5 is a mechanical lock-type safety interlocking switch from the GS series, engineered to monitor and lock the status of safety doors, guardrails, and protective covers on industrial machinery. This device prevents unauthorized access to hazardous areas while the machine is operating, ensuring personnel safety in accordance with the highest international safety standards. The switch detects whether movable machine guarding such as doors, fences, and covers are opened or closed, and triggers appropriate machine stoppage when unsafe conditions are detected.
The GS-51P5 features a standard type configuration with PNP transistor outputs and a fixed 5-meter cable with 8 conductors. The mechanical locking mechanism provides a locking force of 2,000 N or more, ensuring that the guard door remains securely closed under operational conditions. The switch is designed for power-to-release locking operation, with control output via two OSSD (Output Signal Switching Device) channels for redundant safety signal transmission.
| Manufacturer | KEYENCE Corporation | |
| Locking Type | Mechanical lock type (Power-to-release) | |
| Output Type | PNP | |
| Cable Type | Fixed cable, 8 cores, length 5 m | |
| Locking Force | 2,000 N or more | |
| OSSD Outputs | 2 channels, transistor output, max. load current 150 mA | |
| AUX Output | 1 channel, max. load current 50 mA | |
| Response Time | Lock→Unlock: 220 ms; Unlock→Lock: 220 ms | |
| Enclosure Rating | IP65 / IP67 (IEC60529), IP69K (ISO20653), NEMA Type 3/4X/12/13 | |
| Operating Temperature | -20°C to +55°C | |
| Mechanical Life | 1 million cycles or more (at door speed 1 m/s) | |
| Cascading Capacity | Up to 25 units | |
| Safety Certifications | IEC 61508 (SIL2/SIL3), EN ISO 13849-1 (PL d Cat.2 / PL e Cat.4), IEC 62061 (SIL CL2/SIL CL3), EN ISO 14119 (Type 4) | |
| Material (Sensor Body) | SUS304, PPS, PBT, PAR, PA66, NBR |

High locking force of 2,000 N or more provides secure guard door retention, preventing accidental opening under vibration or pressure conditions.
Two OSSD safety outputs provide redundant safety signal transmission complying with Category 4 and SIL 3 requirements for fail-safe operation.
Power-to-release mechanical locking design ensures that the lock remains engaged under power failure conditions (fail-safe principle).
Exceptional environmental protection with IP65, IP67, and IP69K ratings permits installation in washdown areas, outdoor locations, and high-pressure spray environments.
AUX output (non-safety) provides status indication for machine control systems without compromising safety integrity.
Cascading capability for up to 25 units reduces wiring and simplifies safety system design for facilities with multiple access points.
Wide operating temperature range from -20°C to +55°C supports deployment in unheated industrial facilities and outdoor applications.
High mechanical life of 1 million cycles ensures long-term reliability in applications requiring frequent door openings.
Alignment tolerance of ±2 mm simplifies mechanical installation and reduces door adjustment requirements.
Comprehensive circuit protection including reverse current protection, short-circuit protection, and surge protection for all outputs.
The KEYENCE GS-51P5 safety interlocking switch is deployed across all industrial sectors where machine guarding access control is required for personnel protection. Typical applications include perimeter guard doors on industrial robots and robotic workcells, access hatches on CNC machining centers, safety gates on automated assembly lines, and protective covers on packaging machinery. In food processing equipment, the IP69K rating permits installation in high-pressure washdown environments common in meat, dairy, and beverage production facilities.
The switch is also utilized in injection molding machines (access to clamping area), presses (die change access doors), printing presses (web threading access doors), and conveyor systems (guard panels over chains and belts). For facilities requiring compliance with international safety standards including CE marking, the GS-51P5 provides documented certification to EN ISO 13849-1 (PL e Category 4) and IEC 61508 (SIL 3), simplifying machine certification and validation processes. The cascading capability allows efficient monitoring of multiple access points with reduced wiring complexity, making the GS series particularly suitable for large-scale automated lines with numerous guard doors.



