Posted on December 15, 2012 at 13:27That's the way these cables are designed to function. It would connect to the rear of a PC, or to a USB-to-Serial type adapter.
With like-to-like connectors, in this context, there is the need to cross-over the key lines TX<->RX, etc.
If you are concerned with how this works, or needs to work, I would direct you to look at the pin out configurations of the ST boards, and a PC/USB serial connections and draw flow lines between them. ie the TX on the sending board needs to get to RX on the receiving board.
Again, referring to the schematic you should observe RS232 line drivers, which convert to-from the CMOS 3V levels to RS232 compatible levels. This permits the direct connection to other serial devices. One might be careful about 1980's era devices as the connectoring and pin utilization, and flow control, were far less consistent. When in doubt refer to documentation, or get out a scope/meter and probe out the signals.
