Being a multi-function fiber modem in support of asynchronism RS-232,RS-485 and RS-422 communication interface,UT-277 is the best choice for the connection from remote terminal unit (RTU) to host(HOST) or Supervisory Control and Data Acquisition(SCADA). It supports multiple asynchronism communication protocols including RS-232,RS-485 and RS-422, and it also supports a combination of two of the RS-232,RS-485 or RS-422 interfaces as well as both of the working modes, i.e,Two-line (half-duplex) RS-485 and four-line(full duplex) RS-422.The ability to support RS-485 mode for data TXD or SD sending control greatly improves its compatibility with various kinds of software besides a sharp simplification of control method. Various kinds of fiber connection between asynchronism serial interfaces are supported by UT-277 fiber modem. Both half duplex and full duplex communications through fiber between two asynchronism interface devices are supported with a communication distance as far as 4 kilometers for multi-mode and 20 kilometers for single-mode. The transmission rate for RS-232 can reach a maximum of 115.2KBPS,while for RS-485/RS-422 a maximum of 460KBPS can be achieved.Interfaces of different electric standards can be mixed for use with nice EMI/RFT performance,e.g,RS-232 devices can be connected to RS-485/RS-422 devices,and the interface converter or photoelectric isolator can be replaced from RS-232 to RS-485.Two data signal transmissions are supported by UT-277: data sending and data receiving. At the same time, automatic control circuit is alsoprovided for RS-485/RS-422 data transmission. Zero delay for converting time is achieved. ST interfaces are used for fiber connection. Transmission media: double multi-mode Working mode: asynchronous half/full duplex, server/client mode Power pre-consumption: 12db Working environment: -25? to 70?, relative humidity 5% to 95% See more

Transmission distance: 4 Km for multi-mode Note: need 2pcs UT-277 to create communication.One for Tx; another for Rx. Dimensions: 97mm×65mm×22mm Chassis: metal shell Wavelength: 820nm multi-mode 1310nm multi-mode. Electric standard: RS-232, RS-485 or RS-422 (optional) Indicator light: 3 LED indicators for PWR, TX and RX. Electric interface: RS-422/RS-485/RS-232 Adoption terminal. ST Connectors Transmission rate: 460Kbps Power supply: DC 9V @ 200 mA.