Model S4-8085-04 915 MHz UHF RFID Reader, Modbus RTU/USB/Serial, 24vdc, 4 Antenna port This Reader ports up to 4 addressable RFID Antennas with USB and Serial communications standard on all models, and further offer standard Ethernet, Profinet, Profibus, Ethernet/IP, Devicenet, Modbus TCP & RTU. Two lines of I/O are also standard. This Reader can also write to RFID Tags and has a range tuning feature.