Under Windows, for various reasons, any kernel mode code must be written in C (not even C++) and we use C++ as our main production language.

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True laziness is hard work

$FTD->StopInTask;
$FTD->Purge;
        
#$FTD->SetResetPort;
#$FTD->ResetDevice;
$FTD->CyclePort;
sleep(9);
#get stat, create new $FTD, read data;
[download]

Ok, so I was thinking about this business with the byte number being wrong.
I wondered what would happen if I did not set the Baud, and lo, the same behavior occurred. If I set the baud at some high number, it will just give zeros, as expected.
It should be setting the baud though. I have it set to let me know if there were problems.
FYI, here is the code.


use warnings;
use strict;
use Win32::FTDI::FTD2XX qw(:DEFAULT
        FT_BAUD_2400 FT_BITS_8 FT_STOP_BITS_1 FT_PARITY_NONE
        FT_FLOW_RTS_CTS PFT_MODEM_STATUS_CTS
        );


 my $FTD = Win32::FTDI::FTD2XX->new();
 unless( $FTD->PFT_STATUS() == FT_OK )
    {
    printf( STDERR "FTD2XX::new() failed: %s (%s)\n", 
            $FTD->PFT_STATUS_MSG(), $FTD->PFT_ERROR() );
    exit( 1 );
    } 
  printf( "FTD2XX::new() allocated PFT_HANDLE: %d\n", $FTD->PFT_HANDLE
+() );

  my $numDevices = $FTD->GetNumDevices();
  unless( $FTD->PFT_STATUS() == FT_OK )
    {
    printf( STDERR "FTD2XX::GetNumDevices() failed: %s (%s)\n",  
            $FTD->PFT_STATUS_MSG(), $FTD->PFT_ERROR() );
    exit( 1 );
    } 
printf( "Found $numDevices FTDI devices connected!\n" );


$FTD->PFT_DEBUG(1);
unless ($FTD->OpenByIndex(0))
{
    print "Problem opening Port 0\n";
    return 0;
}
unless ($FTD->Purge(FT_PURGE_RX))
{
    print 'cannot purge';
}
unless ($FTD->SetBaudRate(FT_BAUD_2400))
{
    print "Baud is set\n";
    return 0;
}    

peek_buf();

sub split_len 
{
    my ($len, $string) = @_;
    $string =~ m/.{1,$len}/g;
}    

sub peek_buf
{
    my ($amountInRxQueue, $amountInTxQueue, $eventStatus) = $FTD->GetS
+tatus();

    print "trying to read $amountInRxQueue\n";
    while ( $amountInRxQueue< 45)
    {
        ($amountInRxQueue, $amountInTxQueue, $eventStatus) = $FTD->Get
+Status();
        print "$amountInRxQueue in q\n";
        sleep(1);
    }
    my ($bytesReturned, $readBuffer) = $FTD->Read($amountInRxQueue);
    my $numHex = $bytesReturned*2;
    my $upack = unpack("H$numHex", $readBuffer);
    my @a = split_len(18, $upack);
    print join "\n", @a,"\n";
}
[download]

Solved it. When you init a new FTD, I needed to


sub init_FTD
{
    my $FT = Win32::FTDI::FTD2XX->new();
     unless( $FT->PFT_STATUS() == FT_OK )
  {
    printf( STDERR "FTD2XX::new() failed: %s (%s)\n", $FT->PFT_STATUS_
+MSG(), $FT->PFT_ERROR() );
    return 0;
  } 
  printf( "FTD2XX::new() allocated PFT_HANDLE: %d\n", $FT->PFT_HANDLE(
+) );

#    $FT->PFT_DEBUG(1);
    unless ($FT->OpenByIndex(0))
    {
        print "Problem opening Port 0\n";
        return 0;
    }
    unless ($FT->SetBreakOn)
    {
        print "failed to set brake\n";
    }
    unless ($FT->Purge(FT_PURGE_RX))
    {
        print 'cannot purge';
    }

    unless ($FT->SetBaudRate(FT_BAUD_2400))
    {
        print "Baud is set\n";
        return 0;
    }
    return $FT;
}
[download]


otherwise all the data that comes in is seemingly junk.

That was incredibly painful to figure out. I knew I would get there though, once I asked for other people's assistance. Its the way of things.