serial port error

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serial port error

trying to communicate to device attached to serial port on Xserve through terminal...terminal froze after first try (hardware related), however, now - after fixing hardware - when we try to connect using:

screen /dev/cu.serial 115200

we get two errors in rapid succession:

Cannot open line '/dev/cu.serial' for R/W: Resource Busy
Sorry, could not find a PTY.
[screen is terminating]

any suggestions short of rebooting?

xserve/xserveRAID, Mac OS X (10.4.11)

Posted on Oct 9, 2008 3:29 PM

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Answer 1

Camelot

Level 9

54,339 points

Oct 9, 2008 3:58 PM in response to c. steeley

By default the serial port is in use as an out-of-band management interface (allowing you to connect to the system via a serial connection if the network is down).

You will need to disable this before you can reuse the serial port for any other purpose.

The specifics of how to do this vary by OS version.

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Answer 2

c. steeley Author

Level 1

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Oct 10, 2008 2:13 PM in response to Camelot

thanks for the tip...the hardware manual says to run (as root):

+launchctl remove com.apple.xserve.serial-ports+

but it gives an error that remove is not a proper option. do you have
any suggestions on performing this on 10.4.11?

thanks.

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Answer 3

Camelot

Level 9

54,339 points

Oct 10, 2008 7:16 PM in response to c. steeley

Serial port-based terminal support is, indeed, controlled by launchd in Leopard, but in earlier version it's controlled via a classic StartupItem.

Therefore, you need to look at the file /System/Library/StartupItems/SerialTerminalSupport/SerialTerminalSupport

Specifically, look for the line:

ENABLE SERIALTERMINAL=$TRUE

and change it to:

ENABLE SERIALTERMINAL=$FALSE

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Answer 4

c. steeley Author

Level 1

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Oct 13, 2008 9:53 PM in response to c. steeley

thanks for the help, [unfortunately] rebooting seemed to be the only functional solution. hoping it doesn't happen again.

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