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November 26, 2010


USB console cable for Cisco Catalyst

Cisco’s new line of equipment now use a mini-USB cable for console configuration. There is no longer a need for a USB to serial adapter or a roll-over cable.

Connecting the USB cable on Linux should give you a new ACM device that looks something like this: “/dev/ttyACM0″.

To verify, you can also look through your dmesg or /var/log/messages :

[265430.720082] usb 4-1: new full speed USB device using uhci_hcd and address 4
[265430.914246] cdc_acm 4-1:1.0: This device cannot do calls on its own. It is not a modem.
[265430.914305] cdc_acm 4-1:1.0: ttyACM0: USB ACM device

The easiest way to connect to an USB capable Cisco device is to use screen, however you can still use minicom.

Screen command:
screen 9600 /dev/ttyACM0

The USB cable from Cisco is pin for pin the exact USB A to mini-B that you can find at your local electronics store.

2 Comments Post a comment
  1. Robert
    Jan 3 2014

    When I plug in the USB Micro and hook it up to a switch I don’t get any TTY options that work.

    dmesg / grep tty
    [ 0.000000] console [tty0] enabled
    [ 0.781710] 00:07: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A

    Neither of these works to connect to a switch. If I hook up a USB to serial adapter that works and shows up as ttyUSB0, but the micro usb just doesn’t seem to do anything.

  2. Jan 3 2014

    Normally the cable itself doesn’t register in dmesg (passive device), it is the switch/router/thingy that is the ‘ttyACMX’ device. If you do not see this, then I would check if micro-usb port on the switch is enabled. Other than that, verify that the cable works.

    Good luck!


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