OPT-277 Series is one kind can offer RS-232/485/422 serial port carry transparent optic fiber modem of transmission to get end to user, no need patch cords set up, switch over automatically, and can detect and examine the signal speed automatically, zero delays time to transmit automatically. OPT-277 Series adopt optic fiber transmit, have isolate protection, data privacy is fine, working steady, data, such threats to communication equipment as the wave is welled up and interfered with electromagnetically that the effective one has prevented the abominable environment from being struck by lightning, can work in the abominable and dangerous environment reliably.