Posted by bloggsfred00 on 01/18/07 21:32

Jerry Stuckle wrote:
> bloggsfred00@hotmail.com wrote:
> > Jerry Stuckle wrote:
> >
> >>bloggsfred00@hotmail.com wrote:
> >>
> >>>Jerry Stuckle wrote:
> >>>
> >>>
> >>>>>>I need to read incoming bytes on a COM port but I do not want to have
> >>>>>>the script hang if there is nothing to read.
> >>>>>>
> >>>>>>Is there any way to have PHP interrogate a COM port buffer to see if
> >>>>>>there is any content before reading it?
> >>>>>>
> >>>>>>Any other method to achieve the result would also be welcome.
> >>>>>>
> >>>>>>Cheers,
> >>>>>>
> >>>>>>Fred.
> >>>>>
> >>>>>
> >>>>(Top posting fixed)
> >>>>hackajar@gmail.com wrote:
> >>>>
> >>>>>Windows "COM" ports (like com1, com2, etc) do not have a buffer. They
> >>>>>are a serial interface that connects directly to the CPU (or CPU bridge
> >>>>>I suppose with newer motherboards). You will have to be running in a
> >>>>>loop waiting for data on the COM port to get data off it.
> >>>>>
> >>>>>Think:
> >>>>>
> >>>>>while(0) {
> >>>>> $getData = comportcheckfuntion('com1'); //You would have to write
> >>>>>this function or get one off internet
> >>>>> if($getData) //do your stuff here
> >>>>> else sleep(1); //sleep for a second and then let loop check com port
> >>>>>again.
> >>>>>}
> >>>>>
> >>>>>Cheers,
> >>>>>Hackajar
> >>>>>bloggsfred00@hotmail.com wrote:
> >>>>>
> >>>>
> >>>>
> >>>>Incorrect.
> >>>>
> >>>>First of all, the serial port hardware itself has a 16 byte (or larger)
> >>>>buffer built in.
> >>>>
> >>>>Secondly, the COM port, like all devices in Windows, goes through a
> >>>>driver. Your program doesn't talk to the chip itself; it talks to the
> >>>>driver (through Windows). This driver has two buffers - a transmit and
> >>>>a receive buffer. And IIRC, both are 4K. But I haven't written any COM
> >>>>port software since WINNT, so this may have been increased in later
> >>>>versions.
> >>>>
> >>>>But it has not been decreased.
> >>>>
> >>>>P.S. Please don't top post.
> >>>>
> >>>>
> >>>>--
> >>>>==================
> >>>>Remove the "x" from my email address
> >>>>Jerry Stuckle
> >>>>JDS Computer Training Corp.
> >>>>jstucklex@attglobal.net
> >>>>==================
> >>>
> >>>
> >> > Got it all going using MSComm32.OCX as a COM object using PHP COM
> >> > handling. All very simple when you know how....
> >> >
> >>
> >>(Top posting fixed)
> >>
> >>Yes, you can use the com activex object, and it does help. But it's not
> >>necessary.
> >>
> >>You can even open the COM port as a r/w file if you can accept the
> >>default settings (perhaps set up at boot time). No activex object required.
> >>
> >>P.S. Please don't top post. Thanks.
> >>
> >>--
> >>==================
> >>Remove the "x" from my email address
> >>Jerry Stuckle
> >>JDS Computer Training Corp.
> >>jstucklex@attglobal.net
> >>==================
> >
> >
> > Sorry about the top post Jerry, but that is the way Google prefers it,
> > and the way they make it easy to use. It is actually the way I prefer
> > it too, but I am not about to try to sell that to others. Diversity is
> > healthy.
> >
> > I have come to the conclusion that there is no other way to have
> > reliable asynchronous comms using PHP on Win32 other than using the
> > activex object. So far nobody who says otherwise can say how it can be
> > achieved in any sort of detail.
> >
> > *ALL* other methods that can be implemented with PHP have no method for
> > testing the presence of data before a read, and do not return from a
> > read when there is no data to read. This generally leads to a lockup in
> > the RX side of the comms at some point or other, even with the most
> > careful attention to sequences. dio_read() is a case in example.
> > fread() cannot be specified with a length less than 1 (e.g. zero=get
> > whats there), and therefore falls into the same trap. Perhaps in a
> > perfect world with no comms errors ....
> >
> > I have even tried to implement W32API calls to get the result, but
> > there is no reliable way of doing that with PHP before 6 so that went
> > the way of the dodo too (trapped in a PHP5 world for now). It is
> > returning structures that is the problem.
> >
> > I have happily implemented MSComm32.ocx with the ultra reliable results
> > I needed so the question has become moot for me just now, but if you do
> > know of a way (in detail) then I would be most interested for future
> > projects.
> >
> > Cheers,
> >
> > Fred.
> >
>
> (Top posting fixed)
>
> A. Because it upsets the flow of the messages
> Q. Why is it so bad?
> A. Top Posting
> Q. What is the most annoying habit on usenet?
>
> Possibly that's the way you prefer it, but the standards for this group
> include bottom posting. You will get more attention when you follow the
> standards. Many people just skip over messages which include top posting.
>
> And I highly suggest you get a decent newsreader instead of Google
> groups. The vast majority of us here do.
>
> As for how to do it - you can use an ActiveX object, as you indicated.
> Or, you can write a small PHP extension which will allow you to interact
> with the IOCTL calls. The latter would have the advantage of being more
> efficient and an ActiveX object, but you'd have to be able to write a
> PHP extension.
>
> As for my other comment - you don't need to use an ActiveX object *if
> you can accept the default settings*. In your case you can't, because
> you don't want the read to block, so you need to use something like an
> ActiveX control or an extension.
>
> --
> ==================
> Remove the "x" from my email address
> Jerry Stuckle
> JDS Computer Training Corp.
> jstucklex@attglobal.net
> ==================

Always happy to follow standards so fiercely defended, especially when
it is the incumbents who do the work.

In theory, if I can write a PHP extension there would be nothing
unachievable. Unfortunately I needed something simpler that mere
mortals could make use of.

I always thought "settings" were configuration, not the underlying
functionality. I thought there was no "setting" in PHP that I could
change that would allow me to unblock. I suppose I have learned
something today.

Cheers,

Fred.

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