This note from the MS docs for CreateFile explain the problem and the solution:

To specify a COM port number greater than 9, use the following syntax: "\\.\COM10". This syntax works for all port numbers and hardware that allows COM port numbers to be specified.

Well, which is it CommPort or SerialPort? ;^)

Seriously, though, show a bit of code so we can get a clue. Even if I had the package installed on my machine, I wouldn't have a way to reproduce the problem without some code to do so. Generally when using a well-used module, you can assume that any errors are on your side of the fence, which is another reason it would be good to show some code.

...roboticus

The module Win32API::CommPort is the low-level guts that underlie Win32::SerialPort, which probably explains the confusion.

---

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

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BrowserUk:

Thanks for the clarification!

...roboticus

Comments in RED:

$PortName = "COM24";
$PortObj = new Win32API::CommPort ($PortName) || die "Can't open $PortName: $^E\n";
# die if the modem is mapped to port that is higher then 9 ("COM24" here).
# "query modem" using device manager is successful.
# When I re-assign the modem port to "COM4", the new works just fine.

$ob->baudrate(38400);
$ob->parity("none");
$ob->parity_enable(1); # for any parity except "none"
$ob->databits(8);
$ob->stopbits(1);
$ob->handshake('rts');
my $baud = $ob->baudrate;
print "baud from configuration: $baud\n";
$ob->write("ATE0X4\r");
sleep 1;
my $result = $ob->input;
print "result = $result\n";

undef $ob;


Thanks,
Kfir