By crap design, do you mean something like this?
Yes that is quite a crap design. There is no negative voltage generator. It won't work with a real RS232 interface but will probbly work with the crap ones you get on PCs.
Crap! Thanks for the tip, Grumpy_Mike. I am reading the output from a digital scale using an RS232 shield from CuteDigi. This shield works great and also allows me to send commands to the scale (like tare, print, etc.), but I can't upload programs while the shield is installed. Another crap design? Now that I've
discovered SoftwareSerial, I want to replace the shield with a simple adapter. Do you think what I ordered will work? I guess I'll find out soon enough...