The ELX4154 analog output terminal is used for the direct connection of intrinsically safe field devices located in hazardous areas classified Zone 0/20 or 1/21. It can be used, for example, to control intrinsically safe controllers for control valves. The output current range can be switched between 0…20 mA and 4…20 mA.

EtherCAT terminals of the ELX series must always be operated in conjunction with the ELX9560 power supply terminal. This terminal generates an electrically isolated output voltage (24 V EX) from the input voltage (24 V DC) for supplying the subsequent ELX terminals. If a new power supply is required, the combination of an ELX9410 and an ELX9560 can be used so that further ELX terminals can be added. The ELX terminal string must be terminated with one ELX9012 or two ELX9410.

https://www.beckhoff.com/vi-vn/products/i-o/ethercat-terminals/el4xxx-analog-output/elx4154.html