Thanks for looking. I just put the code in for completeness. As usually you get moaned at for not including it. Ill rephrase my question.

Its advice Im after from someone who might have done something similar with perl, daemons and serial/usb. What I suspect is that theres a gotcha with Device::SerialPort or something to do with the run levels that Im missing.

When I run it from the command line directly calling the script with -d for debug. syslog shows all the debug I expect to see and it communicates with the arduino over serial/usb exactly as expected.

When I run it through inet.d using "sudo service zoneswitch start" with debug set in the inet.d bash script syslog shows all the debug messages as expected but nothing goes over the serial/usb connection to the arduino. Obviously all errors from the script are lost as Im running it as a daemon using Proc::Daemon.

In both cases there are no errors from the module Device::SerialPort when I pass it the serial port I want. If the device isnt plugged in my script waits and tries again until it is available. So syslog would show waiting debug messages. So the script seems to be connecting to the serial port ok.

Is that enough info, or is there something Ive missed?