FOR SALE: Hewlett Packard 4952A Serial Protocol Analyzer #forsale
Birton - N6UG
When you're working on projects that require RS232 serial connections. This little gem will let you eves drop on the serial data so you can see exactly what's happening.
HP4952A Protocol Analyzer - $75 http://www.hpmuseum.net/display_item.php?hw=1123
This is in working order, I've used it several times for simple RS232 capture.