Installing a USB Serial Adapter on Mac OS X

The easiest way to go about installing our Plugable USB to Serial adapter is by starting with the device.

  • If you want to verify that the adapter and the driver were installed properly click here

Connect the device to the Mac. Once connected click on the Apple icon and on ‘About This Mac’

Click on ‘More Info…’

Click on ‘USB’ on the left and on the ‘USB-Serial Controller D’
If all is well you should be seeing something like this:

Time to get the driver! Fire up Safari and browse to and scroll down to Mac.
Click on the ‘PL2303 MacOSX10.6 dmg’, the Safari Downloads window should come up:

Double click on the md_PL23-3_MacOSX10

Now double click on the PL2303_1.4.0.dmg to mount the image

Now double click on the PL2303_1.4.0 to start the installation

Once the installer comes up click ‘Continue’ to proceed.

Then ‘Select a Destination’ click on your desired drive and click ‘Continue’ to move forward

Now just click ‘Install’ to continue.

You may be asked of your username and password – enter them and click ‘OK’

You’ll get a warning about restarting the computer after the installation is complete. This is normal, click ‘Continue Installation‘.

Installing should start (takes a couple of minutes to complete)

When it’s done you should see this:

Click on ‘Restart’ to reboot the Mac.

 After you restart, check that everything has installed OK.
On the Mac there are two methods to determine this:

Method 1:
Click on ‘Applications’

Click on ‘Utilities’

Click on ‘Terminal’

kextstat | grep prolific
ioreg -c IOSerialBSDClient | grep usb
Your results should be very close to this:

Method 2:
Click on ‘System Preferences’

Click on ‘Network’

Now click on the ‘+’ sign on the bottom left, and then on the ‘Select the interface and enter a name for the new Service’ click on ‘Interface’ – you should be seeing the ‘USB-Serial Controller D’ there.

This will create a “Network” interface for a modem or serial port. Because it’s a serial port, it’ll say “Not Configured” and that’s normal:

From the “Advanced” button you can change default settings (usually not needed). And this won’t change the “Not Configured” message – that’s still ok.

Now finally, you need an application which will talk to the serial port. On Mac, the file which maps to the port is /dev/cu.usbserial. If you have a null modem cable and a terminal program on the other side, the Mac actually has a built-in terminal program called “screen” that you can use to test the connection.

Once that is up and connected (and if the serial ports are set to the same baud rate and paramters), you can type on either side and see the characters come across.


USB Serial on the Mac is a real melding of the very new and very old. If you have any trouble, just visit to see existing FAQs for Plugable’s USB Serial adapter.

Where to Buy

[amtap amazon:asin=B00425S1H8]

135 comments on “Installing a USB Serial Adapter on Mac OS X”

  1. Pingback: Cisco (and Juniper) Serial Console on Mac OS 10.7 and iTerm2 « Layer3

    • jerome

      Hi Dev,

      Thanks for asking. The USB to serial cable does work with Mac OS X V10.7. You’ll be able to use this same procedure to install it.


    • Leonardo Rodrigues

      Just for the records, i could successfully install the driver and use the USB-Serial adapter on Mac OS v10.8.2 (Mountain Lion). The only difference from the tutorial is that i had to alter GateKeeper configurations so a ‘non-signed’ driver could be installed. Before doing that change, Mac OS refused to run the driver installer because it wasnt from Apple nor from a certified developer. After changing that setting, installation went just fine and the adapter works nice !

  2. Reinhard

    Hi David,

    How and where can the baudrate and other parameters be set? I have not yet found any solution to this problem

    Thanks for response.

    • jerome

      Hi Reinhard,

      Once you have the driver installed, the device will show up in the network dialog of system preferences. From there you just select the USB to Serial device, click the advanced button and select “null modem” as vendor. You’ll then be given options for baud rate.

      Hope that helps!

      Plugable Technologies

  3. SvenTomas

    hello . . .

    Thanks for the great write-up. Unfortunately, I hurredly installed the Mac OsX 10.6 driver, and it wouldn’t work, then I realized that I have OsX 10.5. Successfully downloaded it, but then get the error message ‘cannot install, newer version already installed’. I have spent the last hour trying to figure out how to uninstall the earlier version.

    Any help you can offer would be greatly appreciated.

  4. BradB

    I’m bumping into a problem. Using the terminal I keep getting:

    $ cu -s 9600 /dev/cu.usbserial
    cu: /dev/cu.usbserial: System not found
    $ cu /dev/cu.usbserial
    cu: /dev/cu.usbserial: System not found

    I’ve uninstalled and reinstalled the drivers. I’m not sure what I’m missing.

    • Steve

      Your cu syntax is wrong.

      cu -s 9600 -l /dev/cu.usbserial dir

      See man cu.

  5. Bernie Thompson
  6. Evgeny Baskakov

    Hi Bernie,

    Just want to thank you for this great article. It just saved me a few hours of painful internet search for the Profilic MacOSX drivers and the installation steps. With your article, I’ve got it working like a charm.


  7. fab

    Hi mister,
    this method worked for me, many thanks from Rome, Italy 😉

  8. Pingback: Connecting a piano pedal to a computer @ Blog of Adam Warski

  9. brian

    Hey GREAT write up. Thanks so much for this! Working on 10.7.4. Very happy that I don’t need my windows side anymore.

  10. Stephen Lyons

    If I install this on my MAC Pro (Lion) will it be available to work with an application in Windows XP via Parallels Desktop?

    • Jeff Everett

      Hi Stephen-

      Hopefully you’ve already found an answer to this, and the real answer here is to ask paralells whether your version supports mapping a usb device to your VM. From my experience Parallels handles passing a USB device to a VM fine with the exception of network interfaces, which it only knows how to share via a virtual interface.

      Hope this helps, sorry for the delayed response!

  11. Sam Guo

    Great article, work straight away,

    question about screen /dev/cu.useserial
    after run the commend serial output works fine, but I can not roll back to read previous text when the screen output reach the max raw of the terminal.

    is there an commend I can set to roll back 9999 line?

  12. Hugo

    Bernie – Fantastic description for a complete computer biff like me!

    Thanks – Garmin Foretrex 101 now running like a treat on my Mac….

    Good job…

  13. Maikel


    I got it working but I can not type anything into the windos, I have triied CU and Secure CRT and I see the devices booring up but it seems like my keystrokes don’t make it to the terminal.

    Thank you!

    • Jeff Everett

      Hi Maikel-

      We’re happy to try and help with this, however we’ll need a little further description of what you’re trying to accomplish.
      For the record and benefit of anyone else browsing the thread if you’d like assistance with our usb-serial adapter, we’re much better able to help if you explain what you’re trying to connect to, including details like the model number, and what steps you’ve been able to complete successfully.

  14. John P


    I will be moving from PC to Mac, but will need to run a Windows application that uses a serial port, using boot camp. Would I be right in thinking I would need to install this adapter under Windows using a Windows driver?


    • Jeff Everett

      You logic sounds perfect John- we hope this worked out for you but please let us know if you’ve had any issues.

  15. Scooby

    This modem only worked for me after I attached a Null Modem adapter to it – is this normal?

    I was hoping that selecting “Null Modem” under Preferences–>Network–>USB Serial Controller D–>Advanced would do the same in software – yes?

    • Jeff Everett

      Hi Scooby-

      I’m a little unclear on what you’re trying to connect to, but I definitely consider it normal behavior that you’d have to connect something to the adapter before being able to access it.

      Sorry if I’m misunderstanding your question, please feel free to clarify 🙂

    • larry

      A null modem cable acually switches the TX and RX wires in the cable. This is almost never done in software as far as i know.

      • Jeff Everett

        Thanks for jumping in to help clarify, Larry.

        Best wishes-


    • Jeff Everett

      Hi Shashi-

      Thanks for asking and for the informative link. Indeed ours is a standard or “straight” cable, although these should also work for null modem purposes with a null modem adapter. We don’t offer one, and have no particular model recommended, however something like this should work:

      Thanks again for asking and best wishes-


  16. Tyler

    Trying to set up an Epson receipt printer with the adapter. I followed all instructions and in the network panel, when I click connect to the modem it says it cannot connect. Any suggestions?

    • Jeff Everett

      Hi Tyler-

      Thanks for posting with your findings!

      It sounds like this will be some sort of connection/device specific setting. If you’re able to post with some further details about the printer you’re connecting to such as the model number and possibly a link to a manual for the device we’ll do our best to help.

      Best wishes-

      Jeff Everett
      MCITP Enterprise Support Tech
      Plugable Technologies

  17. Chris


    Loaded it all up fine, however my main purpose was that so I can telnet to devices on the serial port.
    My question is running the telnet what would I put after the telnet command to identify the port,

    at the moment I have

    unknown-00-26-08-f5-af-f4:~ chrismccann$ kextstat | grep prolific
    85 0 0x58412000 0x8000 0x7000 com.prolific.driver.PL2303 (2.0.0)
    unknown-00-26-08-f5-af-f4:~ chrismccann$ ioreg -c IOSerialBSDClient | grep usb
    | | | “IOTTYBaseName” = “usbserial”
    | | | “IOCalloutDevice” = “/dev/cu.usbserial”
    | | | “IODialinDevice” = “/dev/tty.usbserial”
    | | | “IOTTYDevice” = “usbserial”

    typically telnet com1 or an IP is put in, but for this device what would I use.

    many thanks,


  18. Chris

    Ah found it already.

    I just use screen instead of telnet so I,

    screen /dev/cu.usbserial

    thanks anyway.


  19. Pierre Desjardins

    I’m trying to connect a USB-serial adapter in order to sync my old Pal IIIc to the Palm Desktop on my MacPro 10.6.8. Obviously the Palm is ancient but I need to have that data within my Mac as I want to phase out my PC.
    Anyway, I only get to the initial screen “establishing a connection” but then…nothing.

    Have any ideas?

    • Jeff Everett

      Hi Pierre-

      Did you successfully install the prolific driver before trying to connect to your palm? Was the USB Serial device added to your network connections as shown in our post?

      If so, feel free to drop us a line at, otherwise you’ll need to go through the steps in this post to install the driver.

      We’ll need to know more about which parts of the process you’ve been able to complete to be more helpful.

      Best wishes-


  20. waudlob

    this is wonderful, i’m new to the macbook pro, and need to make a cisco console connection. I do have a question, I’m struggling to find “screen”, to display my console session (with a network switch).
    Do i need to download software? I’m not sure what is the best method to configure my switches and routers.

    thanks in advance!

  21. waudlob

    hey, i got it! but, i’ve seemed to have hosed up the session (i quit). stating something about could not find a PTY session.

    man, so close!

  22. Denis

    I wonder if anybody knows if there is any issues with the commonly available usb to serial cables that are so commonly purchased unwittingly that are a clone of the official pl2303.

    Prolific seem to be deliberately isolating compatibility against these devices in the newest Windows drivers, and wondered if thats the same with the mac drivers. Its just not worth wasting time putting in drivers to have to fight them out again when prolific deliberately make them to not work.

    Bah humbug @ prolific, not fair to cause issues for consumers when they should target the clone chip manufacturers directly!

    • Jeff Everett

      Hi Denis-

      Thanks for posting with your question. Indeed we can confirm that on Windows, there is code to check and prevent the Prolific driver from working with a counterfeit chip.

      As far as we know the check is only built into the Windows driver, we’re not certain if this is the same for OS X. Sorry we can’t provide more info here- I’d try and test on a lab mac but we don’t have any of the counterfeit cables lying around, only ours, the ones we know work 😉

      If you have one of the counterfeit cables and find that these instructions don’t work, please post back for the benefit of all.

      Again, thanks for posting with your question.

      Best wishes-


  23. Tim

    I use this adapter with my MBA running OS X 10.8.2. My only problem is my Mac crashes after disconnecting the adapter from the USB port. Has anyone run into this issue?

    Thanks in advance for any assistance.

    • Frustrated

      Mine crashes as well after unplugging the adapter from my MacBook Pro running OS X 10.8.2… starting to get very annoyed. 🙁

      • Jeff Everett

        Hi Frustrated-

        The short answer here is that you’ll need to make sure you’re properly terminating any applications or connections using the USB serial device to avoid this issue.

        We’ve actually seen this across platforms (Windows as well) and are communicating the issue back to Prolific, however in the meantime carefully exiting out of applications and killing processes where needed is your best workaround in the meantime.

        Here’s a more detailed explanation as to why:

        Best wishes-

        Jeff Everett
        MCITP Enterprise Support Tech
        Plugable Technologies

      • Alex

        ‘control’+’a’ then ‘|’ before disconnecting the cable will prevent it from crashing

  24. Fazed

    My question is this… I can get terminal to see the device, and I can get screen to work and give me output, but all I get is gibberish instead of the data I should be seeing. I am using a USB to ttl adapter hooked into an ECD meter ( I admit, I am not a computer guru, but I’m at an impasse…

    • Manuel

      Fazed, I would l look baud rate you are using for your device. I just had a similar issue connecting to an APC UPS management interface. if you are using screen try this command: screen /dev/cu.usbserial (Baud Rate). The baud rate is standard 9600 but you can change it by typing in the baud rate you wanna use i.e. 2400.


  25. Jordan

    After following these directions, and the install of the PL2303_1.4.0 appearing to be successful, I do not see the USB serial monitor option anywhere. Whether I look on system preferences under network or in terminal.

    In system preferences/netowrk, when I attempt to add a something, there is no USB option as indicated on this page.

    In Terminal, all I see is

    /dev/tty.Bluetooth-Modem /dev/tty.usbmodemfa141

    I believe the usb/tty.usbmodemfa141 is the Arduino USB driver I previously installed. But I never see a USBserial device or driver.

    I have an Xbee module and Xbee adaptor connected to the computer via a USB cable.

    This is on a Macbook Pro running 10.6.8

    also using CoolTerm I never see the USBserial option, only the USBmodem141 option.

    thans very much for any help, I’ve been struggling with connecting to these Xbee modules for a few weeks now.

    • Jeff Everett

      Hi Jordan (and any others who might be reading this)-

      One reason our instructions would not work is if you have purchased an FTDI chipset based USB Serial Device. Another common reason for the symptoms you describe would be trying to add the USB Serial Device to network connections when the cable isn’t connected to the system. If the Prolific Driver installer works without an error, then the commands below should return values similar to those listed above when run with the adapter connected:

      kextstat | grep prolific
      ioreg -c IOSerialBSDClient | grep usb

      If you are not seeing the expected output from these commands, please verify that your adapter matches the 3rd photo in our post, showing the entry in system profile:

      If your adapter does not match this entry, our instructions unfortunately will not be relevant for your adapter.

      If these instructions don’t work, please email with your Amazon order ID for further support.

      Best wishes-


  26. Pacman


    I’m trying to use a PL2303 USB-to-Serial cable with my Olimex SAM7-P256 board.
    I have the Prolific driver installed, and the device is recognized and appears as /dev/cu.usbserial
    The board has a standard RS232 port.

    It seems that no matter what I do, I get ‘gibberish’ characters. I’ve calculated the baudrate several times, it should be close to 9600 baud (9595) on the microcontroller.
    On my PowerMac G5, I tried using the network control panel to change the baud-rate, but no matter which rate I select, there is no change in the gibberish characters.
    The characters *only* changes when I change the baudrate on my microcontroller board, not on the computer.

    I also tried using cu –parity=none -s 9600 -l /dev/cu.usbserial dir
    -But I still don’t see the characters I’m sending from the microcontroller.

    Which end really controls the baud-rate, the one at the RS232 plug end or the one at the USB-plug end ?

    Any hints ?

    • Jerry Andrews

      Neither end “controls”; they both have to match. Probably, either your baud rates don’t match (this is characterized by characters appearing on the interface “jerkily”–some stuff is recognized as characters, other stuff isn’t), or your bit count isn’t valid (some characters are readable, some aren’t). Parity generally manifests as most characters not coming through, or true gibberish, if the sender is delivering parity but the receiver isn’t receiving it.

  27. Shashank Patel

    Thank you very much. Been searching for a solution since 6 hours. Started working just fine.

  28. Pingback: How to connect to a serial device on a Mac | cmckeeg

  29. rj

    Good day,

    I’m trying to make my mac mini running 10.6.8 to communicate with my UPS, a Liebert PSA ITON 600. I followed all the instructions and I was able to install the driver and even got similar results after typing;

    kextstat | grep prolific
    ioreg -c IOSerialBSDClient | grep usb

    However, the software that came with the UPS still can’t detect any COM port in my mac mini.
    Any ideas?


  30. Pacman

    I am sure I can’t help you, because I gave up on my microcontroller communication, but I’d like to tell you what I would try (if you haven’t tried it already):
    1: Try unplugging your USB-to-Serial adapter.
    2: Open the terminal, type (without the $):
    $ ls /dev | grep usbserial
    3: You should see nothing after the above line, now plug in your USB-to-Serial adapter, then type…
    $ ls /dev | grep usbserial
    …You should see ‘cu.usbserial’ and ‘tty.usbserial’.
    If you see those two device names, I believe you should contact the manufacturer of the UPS.
    If you do not see the two device names, your USB-to-Serial adapter might be defective. Try verifying on a friends computer.

    OK, let’s assume you see the two device names.
    Open your “System Preferences”, then click your “USB-Serial Controller D” (or whatever it’s called), click the [-] button in the bottom of the panel (to remove it!), click “Apply” and quit System Preferences.

    Try your UPS software again and see if it works now.

  31. Pacman

    Oh, one more thing… Your UPS software might be programmed to recognize certain USB VendorID/ProductIDs. If you’re out of luck, they haven’t heard of the PL2303 chipset.
    If you’re lucky, they have made their software so it can recognize a generic serial port (and if you are *very* lucky, the software can be extended by editing the info.plist inside the application, so you can add a VendorID and ProductID yourself).

  32. rj

    Ei I typed the command and I was able to see ‘cu.usbserial’ and ‘tty.usbserial’ but my mac mini still won’t detect the UPS.. I guess I’m out of luck.. haha


  33. Pacman

    You’ve come a long way already. It seems your USB-to-Serial adapter is working.

    Did you also try removing the interface in the System Preferences ?
    Why would you want to do that ?
    Answer: Because exactly this might conflict with the UPS software.
    If it still doesn’t work, add it back in, also try configuring the baudrate to 9600 baud.
    Another thing: Try asking the UPS vendor if the name of the serial port is important.

    You verify that your USB-to-Serial adapter works by connecting either a modem or another computer via a null-modem cable (eg. a cable where only GND is connected and Rx is connected to Tx and Tx is connected to Rx; that’s all that’s necessary). Then open a terminal window on your Mac OS X machine and type
    $ cat /dev/cu.usbserial
    If you’ve connected another Mac OS X machine with another USB-to-Serial adapter, you can type…
    $ echo “Hello” >> /dev/cu.usbserial
    …Then the text should appear in the ‘cat’ window.
    You could also run for a ‘terminal program’ (I think PuTTY will work) on a PC and configure it to 9600 baud, 8N1.
    …Or if you have an easier way, just use that; eg. if you have an old 9600 baud Hayes modem, it would be fine for such tests. -Hmm… I actually have an old Hayes modem here, I could go and see if it works with my adapter. =)

    Also try and look in your manual for the UPS and read what it says about compatibility on the RS232 port. The vendor might have the manual available as a PDF download.

    I just searched the Web and it seems I’ve found their site. Try this page:
    -There are 3 interesting links:
    Product Information, Support and Service, “Customer Issues Department” and “Request technical assistance on product(s) already in use”. Perhaps the first one or the last one is most relevant.

    I’m not sure I can come up with other ideas, but perhaps someone else reading this might have a few suggestions.

  34. rj

    Thanks so much for all your input.. I’ve tried everything.. The interface wasn’t in the System Preferences to begin with so I added it and used different configurations, I also assigned the baudrate to 9600 baud, but still won’t detect… there is an ‘Auto-search for UPS’ feature in the software of the UPS and this shows up in the terminal:

    “Broadcast Message from localadmin@———-.local
    (no tty) at 23:21 EST…

    UPS Monitoring Software Message: Communication Lost: check connection and port
    setting. ”

    It can’t detect the tty… So i guess the UPS doesn’t support the adapter?

  35. Pacman

    I think there’s no problem with the UPS hardware. RS232 is RS232; it’s the same all over the World with all devices; fortunately it’s not messed up like most other standards. 😉
    -But the problem is with the software. Having written software for a PL2303 device myself, I know that there are a few things to do, to write the software properly.
    One thing *not* to do when writing software, is to use ‘/dev/somename’, because this changes like the weather; different device, different name.
    There might be one more thing left to try… If you right-click on your software application, you’ll see the “Show Package Contents” in the contextual menu. Choose this menu item. You’ll now see a folder called “Contents”, open it. In this folder, there might be more than one interesting file. You’ll have to do a bit of hunting yourself, but one thing I can suggest, is that you try dragging “Info.plist” onto your TextEdit application and look at the contents. Try and see if you can find a name of a serial port in there.
    If there’s nothing interesting in that file, try looking inside the “Resources” folder. files ending in .plist are usually the places where the developer would store such things, which could be tweaked or changed without re-compiling the application.

    From the terminal, you can also trying CD’ing to the application’s Contents folder and do a…
    $ grep -R -i “serial” *
    if nothnig found, try “tty” instead of serial. Still nothing ? -try “rs232” or “uart” or “usart”.

    (Just a thought: I find it a bit weird, if the UPS vendor writes sofware to communicate with the UPS via RS232 and the same vendor does not mention anything at all about compatibility or how to actually connect the UPS in the manual – because why then use several months/years on writing the software? -But I guess some companies want to be strange.)

  36. James

    I cannot get my iogear usb to serial adapter to work on my new Macbook Pro. So far I am stuck using it in Windows (Parallels) but would like to have it locally as well…I have downloaded the “GUC232A-Intel.dmg” file from their site..I go to system information->hardware->usb and see “USB-Serial Controller D”…when I launch SecureCRT or network..i only get “/dev/cu.Bluetooth-Modem” as my

  37. Jack

    After installing the driver rried zterm, goSerial and minicom, none of them worked. Screen did the job.

    • Guinn

      I followed the instructions, and got the driver to show in system report, but never in the network control panel. ZTerm worked, showing me that the driver works (and helped as a step), but minicom is the best app for the job- easy to configure, and remotely accessible with terminal. Great site- thanks for the help!

  38. Pingback: A dependable Serial/Console cable for Macs

  39. Pingback: Skywatcher AZ GoTo am Mac mit Stellarium | return (∞);

  40. Pingback: How to find the COM port number on macbook - Mac-Forums Discussions for Apple Products & Services

  41. Pingback: Building usbboot | Dev @ Work

    • Bernie Thompson

      Hi Varera – could you say what version of Prolific driver you have installed? Prolific has been making some updates (mostly targeted at 10.9), so there are a number of versions in the field right now. We’d like to find if one has a problem. If you can email also, we can start a support thread on it. Thanks!

      • RITim

        I reported the same problem a few months ago that Varera is having. I check periodically for updated drivers but I’m running the latest and still have the same problem. The only way to avoid crashes is to shutdown my Mac first, then unplug the adapter. Just closing the lid and unplugging still causes the Mac to crash.

        I would be interested in any updates on this issues.


  42. David Roberts


    Thank you for your comment. We are going to try to reproduce this problem, and if we can, we’ll post our findings here. Also, we would be grateful if anyone experiencing this issue could open a support ticket by sending an email about the problem to Thanks!

  43. Nelson Anacleto

    I have the same problem with me Enttec DMX Pro: My message error is :
    /dev/tty.usbserial-00002014: Permission denied

    Any help ???

    • David Roberts

      Hi Nelson,

      Permission denied errors usually mean you don’t have sufficient permissions to access a device directly. Try accessing /dev/tty.usbserial-00002014 as root through su or sudo.

      Plugable Support

  44. sauly87

    also i have found that attempting to find the right bit rate the screen daemon gets stuck running and will error next time connecting with cannot find PTY – open activity monitor and show all process and find screen and force quit to resolve

  45. jj

    Had to boot up an old V240, found my trusty old usbserial cable, only had iMac so googled driver, found this page, have to compliment author on a simple ABC process that works a treat 🙂

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  48. Chris K

    There’s a new terminal app called Serial available on the Mac App Store that works with the Plugable USB-serial adapter without requiring any drivers. I wrote it to make serial ports easier to work with on the Mac. You’ll still want the driver if you want other apps to be able to use the port, but if you just need a terminal, this may save you some time.

    • gene counts

      Chris: Have read and re-read your post seven times. Would you be able to list a few steps? I have old Dell running Windows 7. Need to transfer everything from this to new IMac. Already transferred Sony laptop over with HDMI cable.
      I don’t understand “terminal app”, “pluggable USB-serial adapter”, etc.
      If you would list, say, five-seven easy steps including what “buttons” to push(for dummies) would be in your debt.

      Would appreciate any and all comments from the community.

      • Patric Neumann

        Hello Gene,

        Please contact me directly at if you need any help. It sounds to me like you are trying to use the serial cable to transfer data between operating systems?

        Kind regards,
        Plugable Technologies

  49. Patric Neumann

    Hello Chris,

    Thank you for taking the time for sharing this with us.This is a great official alternative solution that we can offer from now on.

    Kind regards,
    Plugable Technologies

  50. Pingback: USB Serial Devices with Mac OS X | LowSNR

  51. Ivan Barkovic

    Thank you for posting. I have the same USB adapter and this tutorial works with macbook pro 13″ 2013, OSX 10.9.4

  52. Abner Ortiz

    it does not work with my Yosemite. I have the Belkin F5U257, and f5u409 belkin. It does not work. please help. I have installed everything that this user said, but it still no work. please help

    • Bernie Thompson

      Hi Abner – Thanks for posting. We’re only able to help with our own (Plugable) products. The chipset, driver, or other details could be different with the Belkin. You’ll want to contact them for support. Thanks!

  53. Jaessr

    I searched for hours to find a solution but couldn’t find anything. Is there a way to show which Com Port of the adapter is used??? I have a windows application running with wine were the app asked me for the com port and it’s very annoying to check every port which is listed just to see if i’ve chosen the correct one.

      • Merlin Marschall

        I am using a mac. Wine is a Windows port making it possible to run Windows applications on Mac or Linux. It can use the Mac Hardware such as the adapter and forward it to the Windows application. Nonetheless i found my answer already but thanks anyway

      • Jaessr

        Wine is a Crossover App to run Windows apps on Mac using the Macs hardware. So i didn’t look for informations regarding Windows ;). Anyway i found the solution and anybody who’s interested check the answer i gave Frode Vatne down below 😉
        Thanks anyway

    • Frode Vatne

      Hi did you found the solution for Wine? (Wine is CrosOwer for Mac)

      • Jaessr

        Yes i did. In Terminal you have to go to your Wine WrapperApp dosdevices folder. In my case “cd library/Application\ Support/AudioCore_14162611962482/dosdevices” and then simply enter “ln -s /dev/cu.usbserial com1”
        The AudioCore folder here is your application name so you have to enter a your wrapper name.
        Now com1 will be used with the adapter

        • Jaessr

          but make sure u follow this sites instruction on how to install the driver first!!!! otherwise it won’t work at all

  54. Pingback: USB Serial | d.e.l.o.g

  55. Pingback: Connecter un cable série sur OSX | hidenn

  56. andrius

    After updating my mac to 10.11 I can’t use my USB serial. I tried reinstalling drivers, it installed successfully but I don’t see it in /dev/tty. as it used to be here. Will there be an update for it?

    • David Roberts

      Thanks for posting! The USB serial adapter is not working with the current version of OSX 10.11, as you have discovered. El Capitan is still very much in development, and it is normal at this stage for drivers to not work, then start working again as Apple addresses various functions in each new release. Apple doesn’t give much information to third party developers that allow them to understand the changes Apple is making, and often we can’t know for sure until the final release version is made available shortly before the public release what, if any, driver changes will be needed. If the driver doesn’t work in the final version, we will immediately begin looking for work-arounds while working with the chip maker, Prolific to develop a driver that does work. I’m sorry I can’t be more helpful, but as long as El Capitan is in beta, we won’t be able to guarantee support for it.

      • Jaessr

        The Problem is OSX10.11 does not allow unsigned kext to be loaded except for a workaround i described to andrius (either its the post down or up to this one) The driver itself is fine and i am using it on 10.11. The problem is the unsigned state. What you guys would have to do to make it work again is to sign the KEXT with apple and provide it in a signed state. Thats all.

    • Jaessr

      The enemy is called SIP. A newly integrated feature which does in fact prevents any unsigned KEXT to be loaded. This means the Profilic driver is shown in the system overview but does in fact have no KEXT loaded to make this thing work.
      I’ve found a workaround which is kinda annoying and does in fact work only as long as you don’t plug any other USB devices into the port after getting the adapter to work. This means: If you use the routine i’ll describe in a few moments you have to be aware that after you plug any other USB device into the port you’re using the profilic with you have to REDO all these STEPS!!!!!

      Here’s what you have to do:

      Boot into recovery mode (hold cmd+r during the startup sound)
      Select a desired language for the recovery mode
      click on utilities and then open the terminal
      type: ‘csrutil disable’ (without the marks) (this will disable SIP, if you’re unsure what your csrutil status is simply type ‘csrutil status’ (without the marks)
      open the terminal and type ‘sudo chmod -R 755 /System/Library/Extensions/ProlificUsbSerial.kext’ (without the marks)
      then type ‘sudo kextload /System/Library/Extensions/ProlificUsbSerial.kext’ (without the marks)
      to make sure everything worked and the kext was loaded type ‘kextstat | grep prolific’ (without the marks) (the profilic should be shown
      To secure you system u should enable SIP again (rebbot and use steps 1-3, then type “csrutil enable”


        • Jaessr

          It seems like this issue has been resolved with the Golden Master Version of 10.11 which came out 2 days ago. If not stick to the described procedure but today i did not have to do these steps and it still worked. I hope it’ll stay this way 🙂

          • Jaessr

            Yes it still doeas have the issue with 10.11.1. I found out that if you leave SIP disabled the whole time you can use it normally with having to do my described steps once. This has been the case here and i thought i had turned it back on which gave the impression as if they’ve had fixed it. Unfortunately you have to stick to my procedure described above but if you leave SIP disabled you can plug in any usb device afterwards it will still work. If you reenable SIP you have to do everthing again, as soon as you plug a different device in. I hope this driver gets signed soon with apple because it is a pain in the a**.

            By the way. This method works with any unsigned driver!!! If you have a non working USB device check the /System/Library/Extensions path for a .kext file with the name of your device. if you find it there and your device is not working you can be sure its a signature problem. just use the commands i described above and change the filename of the .kext to the filename you need.

            This helped me very often to get things going. Apple should really overthink it signature policy. It’s just annoying 🙁

  57. Charlie

    Dear All,

    i would like to download Secure CRT for mac os x EI Captain, But can not find. Where does i download. please shared links.


  58. Doug Lewis

    Any tricks to get this to install and work on a MacBookPro running El Capitan? From what I can tell it installs ok, however when I try to connect to a Dell N2024P switch using Serial Tools it shows connected but I can’t get any response from the device.

    • David Roberts

      Hi Doug,
      If you have the Plugable adapter, the latest driver for OS X is properly signed and there is no need to turn off SIP in order to install it. If you are having problems getting it installed, please contact us at and we can help.

      However, reading your previous comment, it looks like SIP isn’t the problem, since SIP will prevent the installation if there is a problem with the driver. More likely there is some configuration issue or connection problem with the Dell switch. A good place to start is to make sure you have the right cable (Null modem or straight) and the correct port settings. If Dell provides a cable, it is usually best to use that one.

      • Doug Lewis

        David, thanks for the response, I should start at the beginning, I have an older Cables 2 Go USB2Serial cable and my research indicated that the driver I needed was this one. It works on a windows PC but since I use a MAC most of the time I was trying to get it to work. However, I have since ordered a plugable adapter and I think it should be here today and I am sure that will solve my problem. I will keep you posted.

    • David Roberts

      Thank you for posting. Yes, it works in Yosemite 10.10.5.

  59. Poppie

    Thanks for these installation instructions. Its works perfectly.

    • David Roberts

      Thank you for posting. If you do the following, do you see the adapter?

      1. Open a terminal window.

      2. Type in

      ls /dev/ | grep usbserial

      3. If your adapter is connected, you should see the following:


      If not, for some reason your Mac isn’t registering the adapter. If you have the Plugable PL2303-DB9 adapter, please contact us at with your Amazon order number for it. We can do some troubleshooting to find out what the problem is.

  60. Alfonso Sanchez

    Hi Bernie,

    Just want to thank you too, for this great article.
    It just saved me a few hours of painful internet search for the Profilic MacOSX drivers and the installation steps.
    With your article, I’ve got it working like a charm in a few minutes…
    THX Bro!!!

  61. Richard Gahan

    I’ve instlalled GPSDump and PL2303 drivers onto Mac using High Sierra 10.13.6. GPS Dump can see and recognise the usbserial. Click on Flytec to download from 6015 but I can error message – GPS Access Error Product Read Error” Any ideas / suggestions?

    • Pat

      Hi Richard,

      Thanks for reaching out to us, I am sorry the software is not correctly detecting the connection to the GPS hardware, there are potentially a large number of issues that can be causing connection problems. We have recently updated our Serial Adapter driver to improve connectivity in macOS ( ), if you are unsure if you have the latest drivers please reach out to our support team directly via email at ‘’ and we can provide direct support with more details then through this comment system.

      Thank you,
      Plugable Technology

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