OK, thanks for the discussion so far.
I will now re-explain :)
I have permission to read/write from the serial port; I am not running the
script as root.
The filehandle opens exactly as expected. I can crash the dive computer
interface by writing random garbage to the serial port if I reverse the
direction of the filehandle (it's not very resilient, and my computer is
not one I can calibrate so the input is invalid anyway). This, however, is
Not Good as it will eventually lead me to wipe the stored dives I have on
there, and that's not something I want to do too often.
I can happily control the serial interface in terms of baud rate, flow
control, parity et al. I can raise and lower the DTR and CTS flags (lines)
when I need to. I can send the appropriate ACK or NAK signal as
required. I can do all of this from within Perl using POSIX::Termios or
the Win32 serial port module, or within a shell environment (more
limited).
I cannot, however, read any data - at all - back from the device in
question. I know the cable works, because I ran the whole unit on a W2K
platform earlier today and it worked a treat.
The problem I seem to have is actually reading the data - I know it's
there, I just can't seem to get it into a usable state!
If anyone has a handy LED readout serial tester I could borrow, now that
would be useful...
Ta anyway
Graeme
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