Auto sense serial signal rate, zero delay automatic transmit Multi-mode 2KM, signal-mode 20KM, 40KM, 60KM The Model277/A ... ,consumption 2W3.Internal or external power choice.4.Multi-mode 2KM, signal-mode 20KM, 40KM, 60KMCommunication Standard Accord EIA ... Electricity port transmissionRS-232 port 15MOptic port transmission Multi-mode 2KM, signal-mode 20,40,60KMLoading point to pointInterface protection ...