The Model 2089 is Patton's first high speed EIA-574 (RS-232 on a DB-9) to RS-485 interface converter. Supporting async data rates to 115.2 kbps over one or two unconditioned twisted pair, the Model 2089 passes one control signal in each direction. The Model 2089 can handle up to 50 terminal drops in a multipoint polling environment; yet it is small enough to plug directly into a DB-9 serial port…and requires no AC power or batteries for operation. The Model 2089 has five configuration parameters, allowing the unit to be "fine tuned" to a variety of point-to-point or multipoint applications. Silicon Avalanche Diode surge protection is standard as well. Amazing!