what usb -> serial adapter should i get?

i got a new laptop about a month ago and it dosent have a serial port on it. my parents told me that they would buy me a usb to serial adapter if i tell them which one to get. basically i need to know which one to get.

ps im running windows xp

I’d wait to see if the RC stays the same in 2007 before purchasing an Serial/USB adapter.

Well, this is discussed in this thread:
(I’m a little embarrassed after reading this thread; the thread creator is none other than the programmer I worked with on T3 last year…:o )

I have noticed that it isn’t the hardware that matters so much as the driver that comes with it. It’s really a shot in the dark.

Ensure there is a good return policy on the one you’re going to buy, and go for it. Try it out. Return it if it doesn’t work.

I would tell you what I’ve got, but I am not even sure, there is no brand name or model number anywhere on either of my converters.

Good luck…


That one might be a better bet. All the ones I’ve had are based on a Prolific chipset; I’ve gotten drivers from their website:

It’s good to see that Prolific doesn’t have a monopoly.


EDIT: Some of the devices I’ve used with a Prolific chipset have become flaky, so you might try the Parallax first.

good idea but i would still like to program the old bots.

For the holiday season, I bring the gift of wisdom!

Please search before you post!

And all of these links to just some of the other threads I found on the same exact topic…


I suggest the 6 Ft. (1.8m) USB-to-Serial Port Cable… Model: 26-183 that is available at all radio shacks. This is the same adapter that the VEX programming kit has, and if FVC are using it, then I think it is a big hint that it is good. Yes it is a little pricey, but it is worth the quality.

I bought a Keyspan USB->Serial converter, and have been very happy with it. It works for me under both Windows and Linux.

I’ve had good luck with the RadioShack one included in the VEX programming kit.

There’s the Vex one, and there’s also this Keyspan one I use:


It’s slow though, most of them will be, they’re meant for PDAs, not interfacing with this kind of hardware.

Also if you’re feeling adventurous you could try an electronics project and make your own based on this nifty sucker:

some older laptops have a serial port on the docking station, and you can buy some of those docking stations dirt cheap on ebay…like the one for my 700 mhz small/light Dell L400. And this docking station is really no more bulky/heavy than some of the usb/serial adapters are! ymmv

that would be cool…but the new alienware laptop i have dosent have a docking station that i know of.

i may try to build my own :ahh:…then again maby not…lol :slight_smile:


You might look into PCMCIA serial cards. I have had nothing but problems with the multitude of usb adapters i have tried. These would provide a true serial port.

Don’t by a Belkin! I also recommed the Prolific cable. I’m going to order the Paralax one though to try it out. Anyone see a cardbus express 3/4 rs232 adapter?

Parallax is based on the FT232RL I took some important points from the data sheet ( http://www.ftdichip.com/Documents/DataSheets/DS_FT232R_v104.pdf ):

• UART interface support for 7 or 8 data bits, 1 or 2 stop bits and odd / even / mark / space / no parity.
• Fully assisted hardware or X-On / X-Off software handshaking.
• Data transfer rates from 300 baud to 3 Megabaud (RS422 / RS485 and at TTL levels) and 300 baud to 1 Megabaud (RS232).
• 256 byte receive buffer and 128 byte transmit buffer utilising buffer smoothing technology to allow for high data throughput.
• FTDI’s royalty-free VCP and D2XX drivers eliminate the requirement for USB driver development in most cases.
• In-built support for event characters and line break condition.
• FIFO receive and transmit buffers for high data throughput.
• Adjustable receive buffer timeout.
• Synchronous and asynchronous bit bang mode interface options with RD# and WR# strobes.
• New CBUS bit bang mode option.
• Support for USB suspend and resume.
• Support for bus powered, self powered, and high-power bus powered USB configurations.
• Integrated 3.3V level converter for USB I/O .
• Integrated level converter on UART and CBUS for interfacing to 5V - 1.8V Logic.
• True 5V / 3.3V / 2.8V / 1.8V CMOS drive output and TTL input.
• 3.3V to 5.25V Single Supply Operation.
• Low operating and USB suspend current.
• Low USB bandwidth consumption.
• UHCI / OHCI / EHCI host controller compatible
• USB 2.0 Full Speed compatible.

Royalty-Free Drivers For:
• Windows 98, 98SE, ME, 2000, Server 2003, XP.
• Windows Vista / Longhorn*
• Windows XP 64-bit.*
• Windows XP Embedded.
• Windows CE.NET 4.2 & 5.0
• MAC OS 8 / 9, OS-X
• Linux 2.4 and greater
• Windows 98, 98SE, ME, 2000, Server 2003, XP.
• Windows Vista / Longhorn*
• Windows XP 64-bit.*
• Windows XP Embedded.
• Windows CE.NET 4.2 & 5.0
• Linux 2.4 and greater

We have had no problems with the IOGear GUC232A.

If you want a real test of an adaptor, just hook it up to the dashboard, switch it to RC mode, and start reading data. Because the dashboard is set to the highest baud normally supported (115200), any USB adapter not able to handle it will bork.

Any adapter that handles this amount of data will be able to download code as rapidly as a native serially port. I’m not saying others won’t, they’ll just go slower.

The dashboard runs at 19200.

Any adapter that handles this amount of data will be able to download code as rapidly as a native serially port. I’m not saying others won’t, they’ll just go slower.

No, for a few reasons. First, like I mentioned above the dashboard does not run at 115200 so this test won’t work. Second, and much more importantly, is that these USB->Serial adapters are fully capable of 115200 speeds - that’s not the problem. The problem has to do with buffering built into the USB->Serial adapter and the nature of the USB protocol. These adapters buffer up data coming from the serial port and only transmit it to the PC at certain intervals, either when the buffer fills or when some sort of timeout expires. This adds lots of latency since the way the IFI downloader works is to send commands to the RC and then wait for a response. So, each response takes a while longer than it should, which slows down the overall transfer. This is probably also why some just plain don’t work at all.

You know, a little voice inside said I should do my homework before posting…

As an addendum, my post was partly based on my own experience with a USB adapter. Downloading worked, but dashboard didn’t. Don’t remember what adapter or from whom. It was purple and had a USB B port (the square one).

This is an incredible little chip by FTDI. We use them at work at their highest baud rate. We also run them for days at a time. They work great.