Historically, Optec's products and instruments have used a serial communication protocol to communicate with an external computer.  Optec's RS-232 protocol implementation is a 3-wire subset of the official RS-232 specification.  Over the years, our implementation has proven to be quite robust.  Our latest cable product is a unique 3-wire RJ-12 to USB direct connect Serial/USB Cable designed especially for the TCF-S, IFW, and Pyxis rotator.