A:
In order to meet different industrial control systems and safety requirements, safety light curtains usually provide four output modes:
1. PNP (common)
· The output is positive voltage (+24V DC), and the output is high when a safe state is detected.
· Applicable to most PLCs and relay input systems of the "positive trigger" type.
· Advantages: strong anti-interference ability and good market compatibility.
· Commonly used in European equipment and automation control systems.
2. NPN
· The output is negative voltage (0V, grounded), and the output is low when a safe state is detected.
· Applicable to Japanese control systems or NPN input PLCs.
· Disadvantages: Slightly lower anti-interference ability and more rigorous wiring requirements.
· Commonly used in some older models or equipment in specific Asian markets.
3. Relay output (Relay)
· Signal output is carried out through dry contacts, without considering voltage polarity, suitable for high voltage or isolation requirements.
· Advantages: strong versatility and wide adaptability; can be used to control high power loads.
· Disadvantages: slow response speed (usually tens of milliseconds) and mechanical wear.
· Commonly used in traditional mechanical equipment and control circuit isolation occasions.
4.OSSD (Output Signal Cut-off Device)
· A semiconductor output method (usually PNP type) dedicated to safety light curtains, with dual-channel redundant output to achieve PL e / SIL3 level safety protection.
· Features: high safety level, strong fault detection capability, and self-diagnosis of safety circuits.
· Commonly used for robot perimeter protection, hazardous area protection, and high safety demand occasions.
