11
- December
2010
Posted By : Gom Jabbar
OS X Snow Leopard and USB-to-Serial Adapter

These days, I’m a network consultant. A post-modern itinerant witch doctor, wandering from village to village to shake my chicken bones over the sick.

Unless I’m working on a large project, my day typically involves trotting from one customer site to another. Some of the jobs are regular onsite maintenance stuff. Nothing’s broken, per se. I’m just there to make sure everything is kosher in the state of Denmark. Perform scheduled upgrades, inspect the event logs and monitor performance. Some of the jobs are what we call “Break and Fix”, which means that something has gotten buggered and it needs to get unbuggered ASAP. Might be a server issue, a network issue, or PEBKAC. Nobody onsite knows how to fix it, so they turn on the Bat-Signal and I hie my ass thither.

Since I usually do not know in advance what issues I may have to deal with during the course of the day, I travel with a backpack full of of useful equipment. A laptop running Windows 7 and a Ziploc bag full of cables. Console cable, crossover cable, straightthrough cables of varying lengths. USB hard drive full of IOS images and installers. A small computer toolkit in my scooter. A tiny bottle of hand sanitizer dangles on my keychain, useful after touching all those user keyboards (and users). My favorite customer likes to tease me because I carry computer gear in my handbag. Wi-Fi detectors, hex keys and a terabyte worth of data jumbled up with tubes of lipstick.

I’ve always used a Windows laptop to console into Cisco gear. These days, my laptops do not have serial ports, only USB ports. So I connect a console cable via a USB-to-Serial adapter. Fire up Putty or SecureCRT and I’m in. Today, I’m setting up a home lab to practice some Cisco ASA configs, and my home machine is a MacBook Pro running OS X 10.6 (Snow Leopard). I’m wondering if my USB-to-Serial adapter will work with my MacBook. I know that some adapters are Windows-only, and even some Mac-compatible drivers are a bit dodgy. I’ve only ever used this adapter with a Windows machine.

This is my much-beloved no-name USB-to-Serial adapter. So reliable, never fails me. I can’t remember where I bought it, and the packaging in which it came is long gone. No markings on the adapter either. How am I going to get it to run with my MacBook if I can’t tell what chipset it uses? I may need to find Snow Leopard-compatible drivers, and I need to be able to identify the adapter in SecureCRT.

My beloved FTDI USB-to-Serial Adapter
My beloved FTDI USB-to-Serial Adapter

When I plug the adapter into one of the USB ports in my MacBook, I open Terminal and do a

ls -l /dev/tty.*

to see what serial lines I have. This is the output:

crw-rw-rw-  1 root  wheel   11,   2 Dec  9 23:49 /dev/tty.Bluetooth-Modem
crw-rw-rw-  1 root  wheel   11,   0 Dec  9 23:49 /dev/tty.Bluetooth-PDA-Sync

Damn. No USB-to-Serial adapter.

I check the Console to see if any messages were generated when I plugged in the adapter. They might give me a clue as to the vendor. Alas, no joy. I have better luck in the System Profiler, under Hardware | USB. The USB Device Tree lists a “usb serial converter”. The Vendor ID is in the details pane.

USB Device Tree in System Profiler
USB Device Tree in System Profiler

A quick Google of the vendor (Future Technology Devices International Limited a.k.a. FTDI) yields a drivers page:

http://www.ftdichip.com/Drivers/VCP.htm

And they have Snow Leopard-compatible drivers! I do a Jon Stewart happy dance.

I download the DMG for the 2.2.14 version and pick the FTDIUSBSerialDriver_10_4_10_5_10_6.mpkg installer.

Now when I do a

ls -l /dev/tty.*

I get:

crw-rw-rw-  1 root  wheel   11,   2 Dec  9 23:49 /dev/tty.Bluetooth-Modem
crw-rw-rw-  1 root  wheel   11,   0 Dec  9 23:49 /dev/tty.Bluetooth-PDA-Sync
crw-rw-rw-  1 root  wheel   11,   6 Dec 11 02:13 /dev/tty.usbserial-ftDIDRRX

Brilliant. I now have the name of the adapter. It is tty.usbserial-ftDIDRRX. SecureCRT finds the adapter immediately and once I set the baud rate to 9600, I am in like Flynn.

SecureCRT
SecureCRT

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