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Serial Console on OSX

13th April 2008 by 17 Comments

I bought a USB Serial port that had MAC drivers. Check before you buy it that it has drivers. Not all USB Serial have MAC support. I assume that you have installed the correct drivers from here.

First, open Terminal (Applications/Utilities/Terminal). Next, type

ls /dev/tty.*

to get a list of your serial lines. Pick the one that you want to open. For example, my list looks like this:

gf:dev gf$ ls -al tty.*
crw-rw-rw- 1 root wheel 18, 4 Jan 25 07:32 tty.Bluetooth-Modem
crw-rw-rw- 1 root wheel 18, 8 Jan 25 07:32 tty.Bluetooth-PDA-Sync
crw-rw-rw- 1 root wheel 18, 10 Jan 25 09:20 tty.PL2303-0000103D
crw-rw-rw- 1 root wheel 18, 0 Jan 25 07:32 tty.SerialPort-1
gf:dev gf$

And I know /dev/tty.PL2303-0000103D is the USB-to-serial adaptor becuase it’s connected, if you unplug it the tty.PL2303-0000103D stops being listed.

Knowing the serial port, you can just type screen portname datarate to show the serial data on the screen. In my case, it was:

screen /dev/tty.PL2303-0000103D 9600

To quit the screen app, type control-A, then control-.

Postscript

I don’t think that this is very complete, but it worked for me and might help you to get your USB serial working. Please let me know if there anything I can add to complete this piece.

Update 2008/12/28: A reader has pointed out this article is based on a similar article at†http://www.tigoe.net/pcomp/resources/archives/avr/000749.shtml. I must have copied some of the text and then mistakenly believed it was my own. Apologies for this mistake.

Filed Under: Cisco, OSX Tagged With: ,
About Greg Ferro

Greg Ferro is a Network Engineer/Architect, mostly focussed on Data Centre, Security Infrastructure, and recently Virtualization. He has over 20 years in IT, in wide range of employers working as a freelance consultant including Finance, Service Providers and Online Companies. He is CCIE#6920 and has a few ideas about the world, but not enough to really count.

He is a host on the Packet Pushers Podcast, blogger at EtherealMind.com and on Twitter @etherealmind and Google Plus

  • http://bcarroll.typepad.com Brandon

    I bought the keyspan serial adapter and it had a CD with MAC drivers. Installed it, plugged in the keyspan to a switch and fired up Zterm. Zterm gave me a drop down of options on how to connect. Key was one of the options. I chose it and was connected. I too stumbled around for a few days before i got it working.

    Brandon

  • http://etherealmind.com Greg Ferro

    I am sure that some people know how to do this, but for me, I had to work at it a little bit. There are some days when I just wish my first job was with *nix, my life would have been much simpler.

  • John

    Note that the short form of “Macintosh” is not a TLA.

    • http://etherealmind.com Greg Ferro

      Sadly no. But I like the idea

  • Someone
    • http://etherealmind.com Greg Ferro

      It would seem that I owe an apology as I must have taken at least some part of this article from http://www.tigoe.net/pcomp/resources/archives/avr/000749.shtml.

      If I try to remember I think I found a few references around the internet and had some notes that I had captured. I use a text editor and will cut/paste these notes. I must have forgotten or missed recording where I found those notes and when I later read the notes figured I must have written it – the author has the same tone as I do.

      I have made a note in main article referencing the original post. Thanks for pointing it out, it wasn’t deliberate.

  • Pingback: Serial Console Communication from Mac OS X « Code Ghar

  • http://www.garysmith.org.uk Gary Smith

    The PL2303 chipset based units are reasonably well supported under OSX since 10.4 now, and most USB serial leads are PL2303 based. There’s drivers available from Prolific, the manufacturers of the chipset and also an open source available through Sourceforge. However, there still seems to be an ongoing issue with sending breaks through the cable in that they get, er, broken. But otherwise, if you’re looking for a cable then try to ensure it’s PL2303 based.

    Cheers,

    Gary Smith

  • gok

    Using this, how could we send a break?, any key combination?

  • cloudpunch

    Has anyone found a way to make this work on OS X 10.6.2 with unlimited (or at least increased) scrollback? I’ve done mountains of research, but I’m no programmer. If anyone has (or can figure out) a usable applescript, I would extremely grateful!

  • Pingback: A Look at goSerial - Console Break for Network Devices on OSX | My Etherealmind

  • http://asnumber.net/ Matthew Walster

    Doing “screen /dev/tty.PL2….” gives me a screen with the serial cable connected, which is great – but any idea how to get a second serial connection up? It’d be quite nice to have a screen split and viewing the output from two routers at the same time…

  • Dennis

    Screen is a very powerful tool for multiplexing several virtual display screens on a single ‘real’ screen.

    There are a large amount of commands available to screen using Ctrl+a followed by a command letter, for example Ctrl+a ? provides the help screen listing the commands.

    You can log each screen using Ctrl+a H which is good for console logging

    You can add a new screen using Ctrl+a c or Ctrl+a Ctrl+c

    You can access the screen command line with Ctrl+a :

    You can also send a break sequence with Ctrl+a b or Ctrl+a Ctrl+b however this will send the currently configured break sequence and you can use different ones. I found that Ciscos use one sequence where as Suns use a different one. You can view the screen manual page via ‘man screen’ and find info there.

    Good Luck

  • Hamed

    Thanks! It worked for me perfectly.

  • Raphael

    THANK YOU!!!  After installing Lion, my old app no longer worked, thanks for the CLI instructions.

  • Pingback: Serial Over USB on OSX via Screen!

  • Jake Nelson

    Hi Greg, thanks for this. It works very well with one exception, your instructions on disconnecting the session, I think the command is actually Control+A and Control+ not Control-