[cctalk] Inline Serial Device?

Hello all, I am looking for a device that sits transparently in an RS-232 serial line and upon seeing a particular code go over the serial line ((or sequence of codes) will actual a relay (or a transistor). Something with two DB25s or DE9s and is configurable to what code will trigger the output? Some kind of box? Does anyone know of such a thing? I guess it could be cobbled up with a microcontroller, but hoping to just get something "off the shelf." Thank you 73 Eugene W2HX Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx