The EL2904 TwinSAFE component is a digital output terminal with four channels. It switches 24 V DC actuators with up to 0.5 A per channel and has four fail-safe outputs. The outputs are controlled by a TwinSAFE Logic-capable component via FSoE. The component automatically switches off if it detects an error (fail-stop).

The EL2904 has safety parameters to specifically adapt the functionality to the respective safety requirements. For example, a current measurement at the outputs and a test of the outputs can be configured in order to be able to detect cross-circuits among other things and to react appropriately.

In addition, standard outputs can be activated for the EL2904. As a result, corresponding standard outputs are available in the process image in parallel and internally ANDed with the safe outputs of the EL2904. The safe output signals, which are controlled by a TwinSAFE Logic, thus issue the safe release for the standard signals, which can be triggered by the non-safety oriented control system independently of the cycle of the safety controller and FSoE. This allows faster switching times of the outputs, provided that the safety controller issues the necessary release for the output.

The safety parameters are not stored directly on the component, but are transmitted to the input terminal via a TwinSAFE Logic-capable component when the safety application is started. This simplifies service procedures, because the component can simply be replaced. The safety-relevant parameters are transferred to the new component when the safety application is restarted.

Special features:

• 4 safe outputs
• integrated current measurement
• testing of the channels can be activated
• Standard outputs can be activated with integrated AND connection with a safe output signal

https://www.beckhoff.com/vi-vn/products/i-o/ethercat-terminals/el2xxx-digital-output/el2904.html