Re: [Bacnet-developers] Win32 Port - Timing problems?

[Norton, M. <Mar...@Ac...>]

Here's a brief article on writing a WDF kernel mode driver
http://www.codeproject.com/KB/system/wdf_kmdf_basic.aspx

Here's a WDF version of the inbox serial driver.
http://msdn.microsoft.com/en-us/library/dd163311.aspx

Maybe these links will be useful if someone wants to take on the challenge.


Mark Norton
Manager of Engineering
Acuity Brands Controls
Cell: 404 731 6793
Office: 770 860 3636


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-----Original Message-----
From: Steve Karg [mailto:st...@ka...]
Sent: Wednesday, February 10, 2010 2:22 PM
To: Discussion for developers of the BACnet stack
Subject: Re: [Bacnet-developers] Win32 Port - Timing problems?

Hi Clayton,

Thank you for looking into running MS/TP on Win32.  It will be nice if you can solve the issues to get it working as best it can.

> I'm sure that Steve will jump in soon

Thank for the urging, Jason! I was just watching to see how this problem could be approached from another perspective.

> MS/TP has very intense timing requirements.  As a result, nobody has
> yet been successful in implementing it on Windows or Linux.

As far as nobody - that is probably true of this stack - but other vendors (JCI, Polarsoft) have Win32 drivers that make MS/TP work (thanks for the info, Sam!). I have used Polarsoft BACbeat with this driver, and some USB-RS485 converters work well, and some don't work so well.

However, Chipkin Automation has a user mode application that runs MS/TP (CAS Explorer).  Stephen discussed his application with me at the last BACnet plugfest and shared the open source serial library that he uses in his code.  He mentioned that he had hand optimized his MS/TP state machine code and datalink layer, and was using the processor clock (rather than mulitmedia timer) to get better timings.
I mentioned these and the serial source link in a previous post to this mailing list[1].

I think that changing this stack Win32 serial code to use the overlap mode and the packet send would indeed help, fixing the dlmstp.c for
Win32 optimization, and any other of my "bad" win32 coding practices
(threading) that I have done can be fixed to give at least a "lenient"
timings interface on Windows.

I do most of my PC to MS/TP work using a BACnet router, as Jason has mentioned.

Best Regards,

Steve
[1] https://sourceforge.net/mailarchive/forum.php?thread_name=f4a368e50f215c6b0771875f199ce6f9%40localhost&forum_name=bacnet-developers
--
http://steve.kargs.net/

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