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Lead Contents

Safety Sensor: Light-ON Outputs as Default Control Output

FAQ No. FAQ02328

Primary Contents

Question

Why are control outputs of the Short-range Safety Light Curtain "F3SN/F3SH" are defaulted as the Light-ON outputs?

Answer

From a fail safe point of view, Safety Sensors/Safety Light Curtains require to be designed so that a guarded machine will not perform dangerous operation when any malfunction or failure occurs.

In the Light-ON output mode, the operation part of the machine is through the contact point of the Relay.

Thus, even when current does not flow due to malfunction or failure, the contact point a goes in the open state and the machine does not operate, or the machine performs safe operation.

On the other hand, in the Dark-ON output mode, the operation part of the machine is through the contact point b of the Relay. Thus, when current does not flow, the contact point b goes in the close state and the machine operates, or the machine may perform dangerous operation.

Therefore, Safety Sensors/Safety Light Curtains adopt the Light-ON output mode in consideration for safe use.