'Intelligent' input expansion unit maintains a PLd performance level
With the new Elobau interface, performance level "d" in accordance with EN ISO 13849-1 is still achieved when safety sensors are connected in series.
To ensure the safety of machines and systems, moveable guards such as doors and flaps are monitored with safety switches. To avoid having to wire them individually in the switch cabinet, an interface or an input expansion unit can be used. This means that only one cable is connected into the safety relay. In most input expansion units, all errors cannot be detected when this cascading process is utilised. This makes it difficult to achieve performance level "d" in accordance with safety standard EN ISO 13849-1.
For this reason, elobau has equipped the existing interfaces with "intelligence" in the form of control outputs. This allows each error to be reliably detected with an additional monitoring method even when series connection is applied. Thanks to the electronic monitoring of individual channels, even without the use of a standard PLC, performance level "d" can still be reached. The costs of the new interface and the additional measures are negligible compared to wiring the sensors individually.
The 'intelligent' interface enables the interconnection of up to four safety switches to one sensor input of the safety relay.
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