Generic Serial Tap

The Generic Serial Tap plugin should be used together with a dual-COM serial tap device, such as EZ-Tap RS-232 from Stratus Engineering Inc. Alternatively, you can easily solder your own serial tap cable or assemble one on a breadboard.

The idea is to read all the lines of an ongoing serial (RS-232/RS-422/RS-485) communications using a pair of auxillary “spy” serial links. A pair is needed because half of the lines (TX, DTR and RTS) can only be written to — so we need yet another connection to read those, as well.

The plugin itself works as follows. You specify a pair of ports (DTE and DCE) and the baudrate at which the communication to be sniffed works. After that hit the Capture button and you shall see all the communications (including data, control line changes and status line changes) from the DTE point of view.