With an ever increasing number of off the shelf electronic modules and boards available at low prices, designers are inclined to use these instead of making all their electronics from scratch. In many cases this makes sense as developing say, a PID motor controller or a GPS receiver from scratch requires considerable skill, time and effort. A surprising number of modules still have an interface based on RS232. No wonder, as RS232 is easy implemented on a microcontroller with two I/O pins and a line driver such as the MAX232. In the case where the master is a PC, the serial port is relatively easy to access on both Windows and Linux. Usually modules implement a text terminal interface that decodes single line commands with arguments and generate a reply like this: Tx: cmd arg0 arg1 ... argX/n Rx: cmd arg0 arg1 ... argX/n replyline0/n replyline1/n … replylineY/n A complication occurs when there are a number of RS232 modules in a project, as each requires a serial interface at the mast...