Siemens 3TX7002-3AB00 Interface Relay, Narrow Design, Output Coupler With Semiconductor Output, 1 NO Contact, 12.5mm Width, 24VDC Control Supply Voltage, 1.8A Max Switching Current, 48-264 VAC Switching Voltage, 0.06A Min Load Current, 20A/20ms Short Time

Interface modules are available either with relays or semiconductors. Semiconductor interfaces offer some significant advantages: The electronic components are extremely reliable and have an extremely long service life (refer to the diagram below). The input interface combines the best of both worlds – improved technical features and a lower price. When considering output interfaces, the question of “relay or semiconductor” needs to be taken into account as well as the making/breaking capacity and the number of operating cycles. If a relay has to be replaced just once during the complete lifetime of a machine, then a semiconductor interface will already have paid for itself.