Serial to USB cable?

I have a serial cable for my Garmin Etrex, one side a serial plug the other goes to my GPSR. I am about to get rid of my desktop and only use my laptops but I don't have a serial port on either. Knowing this the serial cable is useless unless I spend another $40 - $50 on a "Serial to USB Converter". So, I cut it to see what and how many wires are inside of it and found only three. I was thinking of making my own cable but I don't understand the difference between the two ports. I saw the GPS 'ible here and it's no help unless you don't have the serial cable already...

Here are my questions:
1. As long as I connect the proper data in, data out and ground to the USB cable shouldn't it work?
2. Are serial ports and USB ports that much different?

I read a lot on the pfrancs website and i noticed a few of the connectors looked like they may have had USB cables hooked to them. I've searched and searched but came up with squat! If you have a really good understanding about USB and serial ports can you please help me or direct me to someone who can? Thanks in advance!

westfw9 years ago
You NEED a "fancy" USB/serial converter, though it shouldn't need to cost $40. Here is a brand-name cable for $20
USB and Serial ports ARE that much different; in particular, a USB cable can have multiple conversations on the same two wires at the same time ("multiplexed"), and it's up for the electronics in the "adapter" to pick up the right bits.
martymunch (author)  westfw9 years ago
Thank you, I was talking to someone else today as well and they told my the exact same thing. I did learn that USB ports and cables make it possible to support up to 175 different plug and play items. Thanks for the link as well, now I have to go rewire my serial cable, dang it... lol
I think you're on the right track. But I don't know for sure. I'm probably not who you're looking for, but I would ask PKM, Goodhart, tech-king, or killerjackalope for help.

martymunch (author)  Lithium Rain9 years ago
Thanks for the heads up.