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Device-Modem-1.47
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Device::Modem::FAQ

This is a Frequently Asked Questions list about Device::Modem perl extension.

What is Device::Modem?

Device::Modem is a perl extension written in pure perl that allows to communicate with modems, or generically with AT command set compliant devices connected to your computer via a serial port.

Who is the author of this work?

Cosimo Streppone (cosimo@cpan.org), an italian guy who works and enjoys writing perl programs and objects. If you want to know more, go to http://www.streppone.it/cosimo/work/

BTW, what is Perl?

If you are asking that, probably you are in the wrong place.

Perl is a wonderful programming language, that cuts development times, helps developer keep mental health, good life-style, doesn't pollute developer's mind, allows complete freedom of style, and (from perl manual), gives you enough rope to hang yourself.

Some starting points:

What is an AT command set?

It is a set of standard commands, also called Hayes, in which (almost) all commands begin with AT prefix and they allow to control a modem, router, whatever device. Also cellular phones work with a subset of standard AT commands.

What is a modem?

What the heck are you doing here? http://www.google.com/search?q=Tech+glossary+modem

What are the requisites of Device::Modem?

You must have:

  • A working computer with a standard RS-232 serial port

  • An AT-compliant device (a modem will do perfectly here :-)

  • A working Perl installation

  • Device::SerialPort module installed if you are on some unix platform. Win32::SerialPort module installed if you are on Win32 platform.

Is it multi-platform?

Device::Modem works close to the serial port communication layer, which varies on many platforms. It relies on Device::SerialPort and Win32::SerialPort modules for all low-level communication layer.

It tries to build a platform independent layer above these two low-level modules, so developers don't need to distinguish among different platforms.

It's been reported to work on Win32, Linux, Mac OS X, FreeBSD, NetBSD, OpenBSD, ARM-Linux and Solaris.

Can I use it for my commercial application?

Yes, it is allowed by its license, that is the same as Perl language. If you are using it in a commercial package, or plan to do so, please inform the author (Cosimo Streppone, cosimo@cpan.org). Thank you.

Why the [insert_you_preferred_feature_here] does not work?

This is an open-source software developed in my little home spare time and for my personal interest and amusement. This module has a test suite, but it is not very extensive, so it is possible that some feature X does not work, or it is not implemented yet or I cannot test it.

If you are in this situation, please contact me and provide the following information:

  • Your operating system version and architecture. Complete output of perl -V command is good for this.

  • Your perl version. Again perl -V.

  • Your Device::Modem, Device::SerialPort and (if you are using it) Device::Gsm version. In case of doubt, send the output of:

    perl -MDevice::Modem -le 'print Device::Modem->VERSION'

Thank you.

Why I keep getting "can't open device: /dev/xxxxx at .../Modem.pm line 468" errors ?

First of all, be sure to use Device::Modem version 1.35+. Probably you don't have the correct permissions to access your modem device (usually /dev/modem, or /dev/ttyS0 on unix and COM1/COM2/... on windows). Or you are trying to use the examples that come with Device::Modem distribution with an older version (Device::Modem <= 1.33). In this case, you should upgrade to Device::Modem 1.35+.

Why I get the error "Can't call method "purge_all" on an undefined value at .../Modem.pm line 545" ?

Again, upgrade to Device::Modem version 1.35+. If you get this error, it means that the communication port could not be opened. Most probably you don't have permissions to access your serial port, or you have used a wrong device name (check your device entry in /dev folder). Maybe you are trying to use the examples that come with Device::Modem distribution with an older version (Device::Modem <= 1.33). In this case, you should upgrade to Device::Modem 1.35+.

This module is pretty slow. What can I do?

Make sure you are using that latest version. From version 1.30, the main "send-command" / "wait-answer" cycle has been sensibly improved for speed, though you now have to specify a timeout if you want the module to wait an answer if modem is not ready.

Probably this is the better compromise...

Can I make a [insert_your_preferred_number_here] euro donation to you for this fantastic module?

Oh, yes! Please feel free to contact cosimo@cpan.org to decide details about this... :-)

Or, if you have nothing wrong with that, go to my Amazon wishlist.

I think you are a ?#!x$*z!#(!* and your software sucks

Uh.

Please contact me, so I can improve my software design, ideas and coding, but only if you explain the reasons of your criticism. Thank you.