The USB-4485-SI-M is an industrial-grade 4-port RS-485 hub, splitter and repeater, with optical isolation of 3000 Volt and ESD protection of 15000 Volt. This RS-485 hub is designed to expand a RS-485 channel in the RS-485 network to four RS-485 channels. The RS-485 hub has one RS-232/RS-485 upstream input port and four downstream RS-485 output ports. Data received from the input channel will be simultaneously multicasting to all the four downstream channels. Data received from the downstream RS-485 ports is forwarded back to the upstream port only, and it is not sending to any other RS-485 ports in the node. When any RS-485 channel has incorrect signals or reverse wire connection, the error LED of that specific channel will light on for failure warning. It is very easy to locate the failed RS-485 channel. The failed port will be isolated automatically to prevent interference to other RS-485 channel in the node, to ensure normal operation of other RS-485 ports in the loop For more details on product, Please refer to http://www.papyrus.co.il/rs-232%20485%20to%204-port%20rs-485%20hub%20splitter%20repeater.htm