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'[EE] FTDI Driver problem'
2008\01\17@171209 by Per Linne

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Hello,

I have two devices utilizing the FT2xxR.

I switch both on. One at a time or simultaneously doesn't matter.

I call FT_ListDevices(&numDevs, 0, FT_LIST_NUMBER_ONLY)
  I get the number of devices using the FTDI chips.

I call a function that opens each device one at a time to test for response and identity.
   This is essentially the procedure suggested by FTDI's code example.
   This is used to recognize my devices and it works as expected at this stage.

I switch off one of the devices. Let's call it device 'A'.
   I call the "recognize my devices" function (RMD hereafter) again and it now
   reports the device that is still on.

I switch on 'A' again and the RMD function reports both devices again.

Now I switch off the other device - 'B'.
   This time the RMD function reports no device at all although device 'A' is still on.
   I step through the RMD function and discover that when it attempts to open device A
   for test, it receives an FT_INVALID_HANDLE status and that's it.
   I can't find any information about this condition in the D2XX programmers guide.
   I can't find anything helpful on FTDI's webpage either on how to attack this problem.

Has any of you out there encountered this problem?
Any hints?

Kind regards,
PerL





2008\01\17@190853 by Robert Young

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When you say "switch off" the device, what function are you calling?

I haven't done what you are suggesting with the FT232BM / RL devices but I have created systems with multiple FT245RLs and after determining which should be communicated I call FT_Close with the handle to the non-used device.  The handles are held in temporary variables until I've sorted out which is which.  So then I simply copy the remaining handle to the "master" handle variable to be used elsewhere in the DLL.  I never reference the other device again.Robert YoungYR spam_OUTConsultingrwyoungTakeThisOuTspamieee.org785-218-5636> From: .....per.linneKILLspamspam@spam@swipnet.se> To: piclistspamKILLspammit.edu> Subject: [EE] FTDI Driver problem> Date: Thu, 17 Jan 2008 23:11:44 +0100> > Hello,> > I have two devices utilizing the FT2xxR.> > I switch both on. One at a time or simultaneously doesn't matter.> > I call FT_ListDevices(&numDevs, 0, FT_LIST_NUMBER_ONLY)> I get the number of devices using the FTDI chips.> > I call a function that opens each device one at a time to test for response and identity.> This is essentially the p!
rocedure suggested by FTDI's code example.> This is used to recognize my devices and it works as expected at this stage.> > I switch off one of the devices. Let's call it device 'A'.> I call the "recognize my devices" function (RMD hereafter) again and it now> reports the device that is still on.> > I switch on 'A' again and the RMD function reports both devices again.> > Now I switch off the other device - 'B'.> This time the RMD function reports no device at all although device 'A' is still on. > I step through the RMD function and discover that when it attempts to open device A > for test, it receives an FT_INVALID_HANDLE status and that's it.> I can't find any information about this condition in the D2XX programmers guide.> I can't find anything helpful on FTDI's webpage either on how to attack this problem.> > Has any of you out there encountered this problem?> Any hints?> > Kind regards,> PerL> > > > > >

2008\01\18@021942 by Per Linne

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With switch off I mean removing power to the device.
The equivalent of pulling the USB cable out. This is
of course not predictable, so it has to be discovered
after it has happened.

Besides the procedure that recognizes my devices, do
this (as you of course know) by temporarily open the
connected devices and then close them again after that.
So there are no handles to FT_Close. The problem is
that it is not possible to test open the remaining attached
device.

My system use from one to three USB devices simultaneously,
so I can't 'close unused devices'. They simply are there or not.

PerL

{Original Message removed}

2008\01\18@075348 by Xiaofan Chen

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On Jan 18, 2008 3:19 PM, Per Linne <.....per.linneKILLspamspam.....swipnet.se> wrote:
> With switch off I mean removing power to the device.
> The equivalent of pulling the USB cable out. This is
> of course not predictable, so it has to be discovered
> after it has happened.

The following threads may help you (but I know next to
nothing of Windows programming).
www.cygnal.org/ubb/Forum9/HTML/000701.html
http://portal.knowledgebase.net/display/2/articleDirect/index.asp?aid=222649&r=0.7124903

The following thread may help you to understand USB to
serial converter.
http://www.cygnal.org/ubb/Forum9/HTML/000945.html

Xiaofan

2008\01\18@080109 by Per Linne

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I kill this thread. The problem was obviously
related to my development hardware. I choose
another pair of devices and then the problem
was gone.

PerL

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