The TC1540 is a two-wire RS-485 fiber modem that can mix or match RS-485 (two-wire and four-wire), RS-232 or RS-422 interfaces. It typically interconnects CPUs or host controllers with remote terminal units, is used in SCADA, traffic control and security applications. Modem supports asynchronous data rates up to 700 KBPS, depending on electrical interface.
TC Communications–Inquire R.S. 132