Schmersal

Schmersal is a German manufacturer of machine safety components: safety interlocks and guard-door switches, solenoid interlocks, safety light curtains, and the safety relay modules and gateways that evaluate them.

The switch is only half of a safety function. What decides the achievable performance level is the whole chain: the sensing device, the evaluation unit, and the final element that removes power. A high-rated switch feeding an ordinary relay does not produce a high-rated safety function, which is a common and expensive misunderstanding.

Coded and RFID-coded switches resist defeat, which is what distinguishes a genuine safety device from a position switch with a safety-coloured housing. Solenoid interlocks add guard locking where a machine takes time to come to a safe state.

Safety relay modules evaluate interlocks, light curtains and emergency stops and decide whether the machine may run. Selection follows the function rather than the catalog: the number and type of inputs, whether stop category 0 or 1 is required, and the target performance level or SIL.

Stop categories are worth understanding before specifying. Category 0 removes power immediately, which is correct for most hazards but wrong for a machine where an uncontrolled stop is itself dangerous. Category 1 brings the machine to a controlled stop and then removes power.

Safety gateways extend the same logic onto a network so that diagnostics reach the controller, which turns a tripped guard from a hunt into a message.

Because these are certified components, we quote against the type designation and identify the manufacturer's stated successor where a type has been superseded, rather than offering a near equivalent.