The EL70W is a single bus RS485 to USB interface communicator, allowing PC to be linked to 16 controllers with maximum distance of 1KM. The software can be programmed into the EL70W, which means it does not require a communicator with built-in software key slot like EL70Y or EL70BS. The EL70W is designed for the site that installed IP controllers and require software license (Sofkey 2) to run Elid software (E.Win, WinPro, E.Time and TimePro).