Serial comm with PHP on Windows

Question

I am looking for a way to communicate with RS232 serial COM port on windows. I have found 2 solutions on the net, one which is not totally free (introduces deliberate delays on the function) and another with limited capability on Windows. The latter can only write to a COM port on Windows, not read.

I can't look at the code of the first solution since it is compiled into a .dll (makes sense, otherwise people can just edit the delay and not purchase it...) and the second one seems only to use fopen() to open the port and later fwrite() to it for writing, just like one would do to a stream. But apparently freading it returns nothing.

I know it's possible as the first solution did it, although it does require Apache to use php-cgi module instead of php5module.

Any ideas?

Solution 1

Every solution above is either inefficient or too much work.

You can just use the PHP-DIO library (dio_fcntl, dio_open, dio_read, dio_write, dio_seek, ...). It's also in the PHP manual's entry for DIO:

This PECL package isn't available by default. To get it for Windows if you have PHP 5.2.x greater than 5.2.6, you can download it as part of a ZIP:

• Thread-safe (for Apache)

• Non-thread-safe (for IIS)

Both of these links were found in http://www.deveblog.com/index.php/download-pecl-extensions-for-windows/

Here is the build from Linux, just get it and do the phpize/configure/make/make install thing.

I don't know whether it should be used in an Apache session, but go for it.

Solution 2

The easiest way to tackle this would be to write a program in another language (such as C++) and then execute it from your php script with system(). Doing Comm I/O in C++ is trivial.

This assumes you have enough access to the server to configure it to allow the executable to be run by php, etc.

Solution 3

Another possible way would be to use the Win32 API through something like w32api_register_function() or ffi and then use serial communications calls to get it to work under Windows.

Solution 4

I had the same problem and already considered writing my own php extension when I came across this solution which is popular with Arduino developers - 'serproxy' (found it at many places, ie. http://www.lspace.nildram.co.uk/freeware.html ) sets up a tcp stack to/from the serial ports and allowed me to use the php socket functions to communicate with it.

Solution 5

Another option is to use an object via ActiveX on windows. There are several, mostly commercial serial objects for COM on windows. You can also expose a .Net based object and register it for COM use as well. Of course, this does presume you have control on the server to register a COM control, as you would need a serial interface.

Another issue is resource contention if this is for use via the Web. If this is for a serial printer, for instance, then a print queue manager would be your best option over direct communication.

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Comments

[rmeador]

I'd recommend you develop your comm program as a PHP library so that it integrates directly with your PHP code. Using system() to call and external executable is a sub-optimal solution.

[SoapBox]

Agreed, but to me that no longer falls under "the easiest way" and becomes "the best way". :-)

[Santiago Porras]

Oh my, where were you when I asked this years ago! Accepting this answer.

[kleopatra]

Note that link-only answers are discouraged, SO answers should be the end-point of a search for a solution (vs. yet another stopover of references, which tend to get stale over time). Please consider adding a stand-alone synopsis here, keeping the link as a reference.