Serial to USB Interface?

[pcgamer4life]

I'm working on a small project that requires the use of pins 2 and 5 of a DB9 connector to interface with my PC. Unfortunately, I don't have a machine that has a serial port. Is it possible to use USB (since I have to have a power source already anyway)?
Some of the schematics I've seen are beyond my abilities, and price range for components(like here (http://www.allpinouts.org/index.php/RS232_serial_to_USB_converter_cable_schematic)), but devices exist like this (http://www.ebay.com/itm/Startech-USB-Serial-RS232-Adapter-Cable-9PIN-39322-/400245670044?pt=LH_DefaultDomain_2&hash=item5d3080409c) that don't appear to have such complex circuitry. Would something like the eBay link work? If so, could I simply build one myself and use generic serial -> usb converter drivers?

Thanks!

[petteyg359]

I have this one (http://www.amazon.com/Plugable-Adapter-Prolific-PL2303HX-Chipset/dp/B00425S1H8/ref=sr_1_1?s=electronics&ie=UTF8&qid=1317332017&sr=1-1), mainly because the chipset was specified, which guaranteed it would work in Linux.

[pcgamer4life]

The thing is I'm going to be cutting the serial end off and just utilizing pins 2 and 5, I don't want to spend $11 on something I'm going to cut up. The $4 from ebay is worth a gamble I suppose.

[noxqzs]

The schematic you have linked is the same thing as the ebay adapter. It is also the same thing as petteyg359 posted, just in a different box. Go the cheapest route, and that definetly counts out the diy project when you only talking 11 dollars.

Instead of cutting the thing up, find an old rs232 extension cable and use that to make your harness.

Also keep in mind that since the adapters use microcontrollers, they most likely will need drivers. Its not plug and play for most.

[petteyg359]

The thing is I'm going to be cutting the serial end off and just utilizing pins 2 and 5, I don't want to spend $11 on something I'm going to cut up. The $4 from ebay is worth a gamble I suppose.

1. You can't just "cut it off". That's where the controller is.
keep in mind that since the adapters use microcontrollers

2. Just stick some wires into the holes, or find an old serial-on-both-ends cable to cut an end off of.

You're going to need a driver, regardless of which adapter you buy. Like I said in my previous post, I spent $11 on it because of the known chipset and known quality drivers available for multiple operating systems.

[pcgamer4life]

Ah, I didn't know that the cheap ones linked had controllers inside them.. the only kind I've ever used had a controller midway through the connector (that was significantly larger), so that's why I was puzzled. Thanks for answering such an obvious question. :)

[Bobnova]

Something to be aware of: There are two types of Serial RS232: Normal, and TTL.
Normal runs +18v/-18v, TTL runs 5v/0v.
They aren't especially compatible, obviously :D



What're you connecting to the PC?

[pcgamer4life]

Building a device to be the intermediary between an optical drive and the PC so I can dump the firmware. Specifically using this schematic.
http://t0.gstatic.com/images?q=tbn:ANd9GcQqOV4ZMJUxpSI1G5PEAWsEEFR43N-_joUaiFD27CNCSWyFFPXytw

I was planning on getting the 5V from a USB lead rather than molex, as well.

[Bobnova]

Given that schematic a TTL level device would work quite nicely for you, google "ftdi cable" and see what comes up.
It takes TTL level serial and makes USB of it.
That schematic takes normal level serial and makes TTL out of it.