USB to RS232 Converter

Replacement:CAB-11304. We're now carrying a new, more reliable USB to RS232 Converter Cable. This page is for reference only.

We do lots of converting from TTL serial to USB (using the FTDI and Silicon Labs ICs). But what do you do if you've got a laptop and need RS232 serial? This is a high quality, low cost, small, and easy to use USB to RS232 converter. Device uses the Prolific IC PL-2303 and supports baud rates up to 1Mbps. Driver support for Windows, Mac, and Linux RedHat.

This converter plugs directly into your USB port on your computer and even comes with a small extension cable and CD for drivers.

Note: We have a handful of these left in stock so grab them while you can!

**Replaces: **CAB-08580


Looking for answers to technical questions?

We welcome your comments and suggestions below. However, if you are looking for solutions to technical questions please see our Technical Assistance page.

  • RocketGuy / about 14 years ago / 2

    We found working drivers for Mac/Snowleopard, the sourcforge open driver for the chip works just fine.

  • Member #331047 / about 12 years ago / 1

    Had problems with the latest driver 1.6.1 giving me "Code 10" error message and not working. I found that has copy of the PL2303_Prolific_Vista_332102.exe driver that works great for windows 7.

  • PlanetaryGear / about 12 years ago / 1

    sad to see the prolific chip in here. There is an identical looking adaptor which has the FTDI chip in it. I prefer the FTDI in every way and have half a dozen of those adaptors that look otherwise like this in service 24/7 on my Mac server without difficulty. I wont waste time messing around with the prolific ones anymore.

  • Hackbat / about 12 years ago / 1

    Been trying to make mine work, after reading through the adafruit forum post I popped it open and discovered NOT a well made adapter but instead a black tar chip with no sort of level converting. I kinda feel cheated, It would be nice if products like this had a warning that it's entirely possible what you're getting won't work.

  • mgimeno / about 12 years ago / 1

    I need a usb to ttl cable. I need RX, TX, GND and the most important: a pin to control ZERO CROSSING, since my purpose is to connect a pc through usb to XM10e (ttl-cmos) and so be able to send X10 commands through europe wire system.

    is this cable the right one for me? or which one Id need? Thank you so much for your help, since as you see, I'm bit noob :)

  • rocketman221 / about 12 years ago / 1

    I got one of these from ebay several years ago and they work great. I use it to connect my old Garmin GPS to my laptop. They use a Prolific PL-2303 IC and work out of the box in Linux, no driver needed. They show up at /dev/ttyUSB* instead of /dev/ttyS* like a normal serial port though. They need a driver for winblows and never connect to the same port twice.

  • Member #263326 / about 12 years ago * / 1


    Just to know if this USB to RS232 Converter is full compatible with Basic Stamps.

    Thanks. PS: Have you done some test using a B.Stamp ?

  • Etronik / about 13 years ago / 1

    Hi, I purchased that usb-rs232 converter in sparkfun, but I haven't found the correct drivers to make it works (windows 7 drivers), I have tried with a lot of drivers on the web but I couldn't find the correct. Somebody has drivers for windows 7? I apreciate your help.

  • WizenedEE / about 13 years ago / 1

    If we could just figure out how to remove the step up circuitry from this, the logic level converter would not be necessary...

  • Member #155322 / about 13 years ago / 1

    Anyone get this to actually work on a w7 (64bit) computer? I have tried both drivers (, and neither work and I don't understand why. Please someone help!

  • syndicated / about 13 years ago * / 1

    On 64-bit Windows 7 Pro I got a code 10 error with the linked drivers.
    I found a link to a working driver on the adafruit forums.

  • billiam2536 / about 13 years ago / 1

    Can this be used the same as one of the ft232xx break out boards, just connecting to the required pins?

  • Member #197303 / about 13 years ago / 1

    I have Windows 7 and I finally (sort of) got this thing working. I tried every driver I could find on the net (at least twice, probably). Several of the more recent drivers (like the one posted by Mitch) seem to work with my ARM7 board. I couldn't get anything to work well with my 8051 in Windows 7 though. I finally used a virtual machine and some older drivers to get it to work. I still have to replug before each load cycle though.

  • Member #87119 / about 13 years ago / 1

    When I use this USB converter to read data from a force gauge, it skips every other reading! (empty string) Anyone else have this problem? (No problem with the gauge on the same computer, same program but using the 9 pin serial port!)

    • Member #87119 / about 13 years ago / 1

      From prolific website: Q Why do I get an Error Code 10 (Yellow Exclamation Mark) after I installed the latest driver?
      A If you are getting an Error Code 10 with a yellow exclamation mark in Device Manager after installing the latest Prolific PL-2303 driver, please contact the cable maker of your product for Prolific chip validity and support.
      Prolific strongly recommend to only purchase USB-to-Serial cables from company-branded products providing technical support. It is not advisable to buy from unknown cable makers (no-brand cables) made in China. Prolific does not manufacturer any end-product cables and will not provide direct support to end-users.
      So SPARKFUN is selling cheap China crap!

  • BT / about 13 years ago / 1

    My driver CD was cracked in shipment (or before). The Prolific site seems to be down. :-(

  • OrC886 / about 13 years ago / 1

    I have a bad experience with these Profilic based serial-to-usb chipsets.
    They drivers are always a mess.
    I would be glad to see an adapter like this from another manufacturer.

    • MikeA / about 13 years ago / 1

      I've also had nothing but trouble with Prolific chipset USB-Serial converters. They just seem to stop working constantly - requiring an unplug/plug to get them working again. And I've also experienced the issue with newer drivers being even worse than the older drivers.
      Please Sparkfun see if you can find a USB-Serial converter that uses any other chipset.

  • Quazar / about 13 years ago / 1

    You may want to update the description; it mentions hex nuts that are not present in the product photos. I think that text only applies to the product that this is replacing.
    [EDIT] Looks better now - thanks! [/EDIT]

  • are these gonna be back in stock

  • adamj537 / about 13 years ago / 1

    Does anyone know if this converter is serialized, i.e. if it is moved from one port on a computer to another port, will the computer be able to recognize it and give it the same port number?

    • Windows assigns ports randomly. Each computer will see it as a different port.

      • adamj537 / about 13 years ago / 1

        Right...but I wonder if the USB chip has a serial number in it? Cheaper USB-to-serial converters (such as certain Prolific chips) have no serial number and so a computer can't tell the difference between two of the same devices plugged into it at the same time. I believe this can be tested by plugging one of the devices into a USB port, then removing it and plugging a different one into the same USB port. If the two devices are assigned the same port number then they are not serialized, but if the computer "remembers" what port numbers are assigned to each converter, then they are serialized. For example, the 232USB9M USB-to-serial converter at B&B electronics is offered in both serialized and locked-serialized versions. (The locked serialized version gives you multiple devices with the same serial number, to purposely be indistinguishable to a computer).

  • Mitch5 / about 14 years ago / 1

    Unfortunately the latest drivers kill this thing for Windows. I can't find the old drivers hosted on a reputable site and I'm pretty sure they wouldn't support Windows 7 anyway.
    Sparkfun - you guys should consider putting the driver information in the description.

  • larwe / about 14 years ago / 1

    The big question being... do the drivers work in Win7 (32-bit)?

  • xealot / about 14 years ago / 1

    I have this connector, these HEX nuts are permanently molded, glued or otherwise welded into this device. I ended up destroying the shroud around the pins to remove them.
    Everything still works, but you should be prepared to break this thing if you have a device that has hex nuts which you are unable or unwilling to remove.

  • jalthaus / about 14 years ago / 1

    So far so good with this product using an XP box, plan to use it with Mac OSX Snow Leopard and Parallels XP partition later.
    However, I did not find it "pretty easy" to "grab a pair of pliers and pop these two hex nuts out of the black plastic housing" w/o damaging the 'connector guide' (the metal shroud around the pins). The connector guide is attached to the piece of metal that the hex nuts are attached to, therefore when you try to "pop" them out the whole piece gets mangled. What's more is that there is a metal piece just below the top connector guide that the hex nuts are also attached to which will likely also get mangled. In the end I just pulled the connector guide off, clipped out the hex nuts, re-bent metal pieces to straight and super glued it all back together. Wasn't too bad, and it doesn't look that bad, but it was not as easy as I expected.
    Try to work the hex nuts around slowly and gently and they may loosen up enough to allow every thing to remain in tact. Don't get me wrong, I'm not dissatisfied, I'm just trying to help others out...

  • Mathieu / about 14 years ago / 1

    The Prolific IC contains GPIO. Did someone test if those were routed on the DB9? Same for power?

  • DaveAllan / about 15 years ago / 1

    Does the PIC-PG1 (sku: PGM-00009) work with this serial port? The documentation for the PG1 specifically says "USB to serial cables have also not been proven to work." but that suggests that some USB-to-serial dongles do work.

    • Ivan747 / about 13 years ago / 1

      In short: no. Even if you manage to access directly to the IO lines of this converter, which may require some really hard hackery or driver coding, it would be too much effort and money to convert the voltage levels this converter probably uses (inverted, 0V to +5V TTL signals?) to +13 and -13 volts for using the PG1 programmer.
      Those +13 and -13V lines are used to give the PIC's MCRL pin the necessary voltage for entering into programming mode.

    • EvanT / about 15 years ago / 1

      I think thats splitting hairs, unless the only reason it wouldn't work it noise in the cable.

    • DaveAllan / about 15 years ago / 1

      I emailed the same question to sparkfun support and got a very uncertain maybe.

  • marosy / about 15 years ago / 1

    It does NOT work with the latest prolific drivers
    The device can't start.
    Howerver it works with PL2303-Driver_XP2K_v204102.
    But still it is preferable that a product to work with the latest drivers!

    • Param / about 15 years ago / 1

      Exactly... that's the problem I had. Where do I get that old driver?

  • Limb / about 15 years ago / 1

    This also works fine under plain old Mac OSX. Use it to program my AVR with AVRFuses and avrdude right within OSX.

  • Doug Wood / about 16 years ago / 1

    I am using VMWare Fusion on the Mac to run Windows in order to use some PC only robotic software on my Mac. I got this adapter to replace my old KeySpan adapter when I found that the KeySpan would not connect to some devices such as the Lynxmotion SSC-32 servo controller from my Mac using Fusion. This adapter works great.

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