The newer ones didn't support the weight and allowed the USB cable to pull partially out of the port. coiled-up serial cable, the newer Keyspans would not. Whereas the older Keyspans would easily support the weight of the adapter + a 10 ft. The lower quality USB socket caused many problems for me. The weaker spring conductors allowed the cable to be pulled most of the way out of the socket, resulting in a lost connection and possibly a BSOD (blue screen of death). Unfortunately, the newer Keyspan's USB socket didn't retain the cable connector nearly as well as the older ones did. The only notable difference was a lack of molded numbers (1, 2, 3 and 4) on the end of the plastic tab in the middle of the port. From the outside, the sockets looked almost the same.

Unfortunately, after Tripp-Lite took over the Keyspan line, they used a lower quality USB socket for a period of time. I keep one in my laptop bag at all times. The Keyspan adapter takes just a few minutes to set up. The Keyspan is extremely configurable, fast, reliable, durable and easy to use. Since I first started using the Keyspan adapter, I've bought over a dozen more for service techs, co-workers and even a couple of bosses. The Keyspan USA-19HS is the cheapest piece of control system communication hardware that I own, and it's probably the most used. It works with straight serial cables, null modem cables, and every type of serial adapter I've thrown at it. I've used it on SLC 5/xx series processors, ControlLogix 5000 processors, Siemens/TI 505 series processors, Keyence laser measurement equipment, modems, serial printers, barcode scanners, Reliance and Rockwell/Allen-Bradley drives, and just about everything else. I've used it with laptops and desktops running Windows 98SE, Windows XP and Windows 7. The Keyspan is inexpensive and has proven to be 100% compatible with everything I've needed to connect to via a serial cable. The first one was purchased after reading recommendations from several control system experts, and I haven't been disappointed. Excellent USB serial port adapters! I've been using Keyspan USA-19HS adapters for years.

Tech2 usb serial