Have you tried initialising the object with the lockfile parameter to obtain exclusive ownership of the port? 
$PortObj = new Device::SerialPort ($PortName, $quiet, $lockfile)
     || die "Can't open $PortName: $!\n";

[download]
This is from the Device::SerialPort documentation.

Hope this helps

Martin

In reply to Re: How to lock other users from using Serialport under Linux ? by marto
in thread How to lock other users from using Serialport under Linux ? by Anonymous Monk

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