Keyence GS interlock switch

In modern industrial automation production lines, monitoring the switch status of safety doors, protective covers, and maintenance windows is the core link to ensure personnel safety and equipment compliance operation. The GS Series safety interlock switch launched by Keyence quickly became a benchmark product in the field of mechanical safety due to its compact size, sturdy structure, and diverse installation methods. This series is divided into Locking Type and Non Contact Type, respectively suitable for high inertia equipment and light load protection scenarios.

However, any safety device will face problems such as wiring aging, mechanical wear, and parameter configuration errors during long-term operation. Engineers often need to quickly obtain technical details and troubleshooting ideas when selecting, installing, or maintaining GS Series. This article is based on the official technical information of GS Series and combined with common on-site situations. It systematically summarizes the selection points, wiring cascade scheme, typical fault diagnosis and replacement steps of this series of safety interlock switches, aiming to provide a practical "handy guide" for automation maintenance personnel.

Chapter 1 Product Positioning and Comparison of Two Major Types

1.1 Locking Type

The locking type safety interlock switch is suitable for equipment that may maintain hazardous energy even after the machine has stopped, such as large flywheels, inertia operated stamping machines, fans, etc. The GS Series locking type has the following core features:

Holding force of 2000 N: Even if the operator forcibly pulls the protective door, it cannot open the locked state, ensuring that the dangerous area cannot be entered.

Power off hold or release optional: Depending on the model, users can choose to keep locked after power off (applicable to high inertia devices) or automatically unlock after power off (applicable to low inertia devices).

Manual release device: In emergency situations or maintenance, it can be unlocked from the outside using a specialized tool.

Lock/Tag Out (LOTO) Design: Metal head with reserved lock holes for easy execution of energy isolation procedures.

1.2 Non Contact Type

Non contact type is suitable for detecting the position of doors, covers, or moving parts that do not require mechanical locking. Its characteristics include:

Wide switch range (ON-OFF distance ≤ 18 mm): Even if the door body undergoes slight deformation or vibration, it can stably output safety signals to avoid frequent false shutdowns.

Metal casing: resistant to mechanical impact and dust environment, with a longer lifespan.

High visibility indicator light: Quickly identify the opening and closing status of the door through large-sized LED.

1.3 Selection Decision Matrix

Application scenario recommendation type key parameters

Inertial shutdown time>5 seconds lock set (power-off holding) 2000N holding force, manual release

Immediately after a power outage, the non hazardous locking type (power off unlocking) requires a power on locking signal

Light load door, sliding door, vibration environment non-contact 18mm switch distance, metal shell

Non contact type for confirming the origin of moving parts as a position sensor

Chapter 2 Core Functions and Design Highlights

2.1 Compact and sturdy balance

The GS Series locking type is only half the size of traditional safety switches and can be installed in aluminum frame or narrow spaces. The non-contact type adopts a mixed structure of all metal head and plastic body, which not only reduces weight but also ensures impact resistance. Both models achieve IP65/IP67/IP69K protection levels and comply with NEMA 3, 4X, 12, and 13 standards, making them suitable for direct use in high-pressure water washing or oily environments.

2.2 High visibility status indicator light

The indicator light adopts a large-sized chamfered design with adjustable brightness (configured through M12 wiring), which can be clearly distinguished from multiple angles. Green constant light indicates that the door is closed and the safety output is ON; red flashing indicates a fault or insufficient locking. This design significantly improves inspection efficiency.

2.3 Built in cascading function

In traditional safety circuits, if multiple safety doors are connected in series, each switch usually needs to occupy an independent safety relay input or use a complex junction box. Each unit of GS Series has OSSD output direct function:

Connect the OSSD output of the first switch to the OSSD input of the next switch, and so on.

The OSSD output of the last switch is connected to a safety relay or PLC safety module.

Up to 32 units can be cascaded while still maintaining the PL d/e level.

After cascading, the status of all switches is transmitted only through a pair of safety signal lines, greatly simplifying the safety wiring of multiple devices.

2.4 Built in auxiliary output and reset function

Each GS Series switch (especially the M12 connector model) provides additional AUX output (PNP/NPN). This output can be connected to a regular PLC input or indicator light to individually locate which door is opened without interfering with the safety circuit. At the same time, some models integrate EDM (External Device Monitoring) and manual reset functions, which can be directly connected to the contactor feedback loop without the need to purchase additional safety relays.