[vox-tech] [OT] Com port hacking dumb device

[Jeff Newmiller]

On Mon, 4 Dec 2006, Alex Mandel wrote:

> So I have this device a TrailMaster TM1550, it a remote camera station
> triggered by infrared. It store events(trips of the IR beam) to some
> sort of solid state memory. They then give you a stereo headset jack
> that plugs into the device and serial cable on the other end to download
> the data.
>
> I happen to have a data downloader from them, but it doesn't seem to
> work. I also have windows software that allows you to download and that
> does work. But what I really want is to make a PDA download the data so
> the I don't have to bring each device back to the office to get data.
> I have the proper cabling to make it all connect but I think I need to
> send the device a signal to tell it I'm ready to receive data.
> I also have a serial port logger application loaded on the PDA, and that
> works with a GPS unit so it should work for this too.
>
> 1.How do I figure out what that signal needs to be.

Documentation is always the best solution.

Oscilloscopes can be used if the signal is one of the RS232 control
signals, but a better solution is a serial sniffer (google for a variety
of options; it is software combined with a special serial cable that
gets in between two successfully communicating devices and records their
conversation).

> 2.What tool do I need to send such a signal.

Linux?

Really... this depends on how you are going to capture the data... because
once you send the signal then data will presumably begin coming at you.

Frequently, the signal is built into a handshaking protocol built out of
binary or ascii bytes that goes back and forth between the receiver and
the sender... if the protocol is ascii-based and you can figure out how to
work it manually at the keyboard, then "expect" could be used to automate
it.  However, for proprietary devices like this the chances of that are
not so good.

> For now the goal is a PPC with windows mobile 2003, but I do have the
> option of a IPAQ with familiar linux on it, although I can only transfer
> to that device via flashcard shuffling at the moment.

I suspect that if your windows software doesn't run on the WM2003 machine,
you should talk to tech support or use a laptop with XP.  If they don't
support WM2003 and are not going to give you the protocol, you are going
to learn a lot before you get it working.  If they will give you the
protocol, you may still learn quite a bit. :)

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