[fpc-pascal] The fpOpen call on a serial port blocks on a Mac. Why?

[Henry Vermaak]

On 11/08/11 05:00, Bruce Tulloch wrote:
> I am using the latest synaser (007.005.002) from the synapse library
> which works just fine with (USB) serial ports on Linux and Windows but
> Mac OSX 10.6 it is proving problematic.
>
> The call which opens the port (synaser.pas:946) is:
>
>    FHandle := THandle(fpOpen(FDevice, O_RDWR or O_SYNC));
>
> where in my case, FDevice is /dev/tty.usbserial.DCUIYCH4.
>
> This fpOpen call blocks indefinitely (i.e. it never returns).
>
> The device is present, working and requires no flow control:
>
> My-Mac:~ admin$ stty -f /dev/tty.usbserial-DCUIYCH4 -a
> speed 9600 baud; 0 rows; 0 columns;
> lflags: -icanon -isig -iexten -echo -echoe -echok -echoke -echonl
> 	-echoctl -echoprt -altwerase -noflsh -tostop -flusho -pendin
> 	-nokerninfo -extproc
> iflags: -istrip -icrnl -inlcr -igncr -ixon -ixoff -ixany -imaxbel -iutf8
> 	-ignbrk -brkint -inpck -ignpar -parmrk
> oflags: -opost -onlcr -oxtabs -onocr -onlret
> cflags: cread cs8 -parenb -parodd hupcl -clocal -cstopb -crtscts
>          -dsrflow -dtrflow -mdmbuf
> cchars: discard = ^O; dsusp = ^Y; eof = ^D; eol =<undef>;
> 	eol2 =<undef>; erase = ^?; intr = ^C; kill = ^U; lnext = ^V;
> 	min = 1; quit = ^\; reprint = ^R; start = ^Q; status = ^T;
> 	stop = ^S; susp = ^Z; time = 0; werase = ^W;
>

Have you tried setting clocal under oflags?  If "open" thinks it's a 
modem, then it can block until it sees carrier detection.  I notice that 
my serial ports have clocal set.

> and the screen command opens and communicates via this port just fine so
> I don't believe there is anything wrong with the device, the driver or
> the state of any port flags when fpOpen is attempted.
>
> Can anyone tell me what I might be doing wrong here?
>
> Note that adding the O_NONBLOCK flag allows the fpOpen to succeed but
> all subsequent attempts to talk to the port return ENOTTY which is of
> course wrong as it is a real (USB) serial (TTY) device.

This should have helped for the modem issue.  Did you remove the O_SYNC? 
  Maybe setting clocal after opening will help?

Henry