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The GUI elements should only be accessed from the main GUI thread. Accessing from another thread sometimes but not always results in an exception. As the others have said, use PostMessage to trigger an update in the GUI thread.
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Is it possible to programmatically under Windows force a USB3 port to operate in USB2 mode, and then at a later time to switch it back into supporting USB3 mode? We need to test that a piece of hardware functions with both USB2 and USB3 connections, and would like to do this programmatically to prevent operator errors.
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It will switch automatically if you plug a USB 2 device in, as the USB 3 pins will not be live. But most PCs these days have both types so it should be fairly simple to do. The only other way I can think of would be in the BIOS somehow, or to remove the 3.0 driver.
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Yes, I know it will switch to USB 2 mode with a USB 2 device. We need to avoid an operator having to plug the device into a USB 3 port, and then moving it to a USB 2 port, as they can be lazy, or make mistakes. We need the switching to be automatic and fast, and some form of switchable hub that connects to USB 2 and USB 3 ports on the PC may be the answer.
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If the device is USB2 then plugging it into a USB3 port will not be a problem, it will run as USB2. I don't quite see what problem you are trying to solve.
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Richard, we have a unit that needs to be tested on the production line, prior to shipping to the customer. The unit must work with both USB 2 and USB 3 connections. I won't go into the reasons why we need to test both connections but we do. At present the operator must manually take the USB cable out of the USB 3 socket, and put it into the USB 2 socket, and vice versa, when requested to do so by the test script. This introduces room for error, as they might get confused, and also they might end up damaging the USB socket since they will do this many times each day.
So a better solution is to have a software controlled way to switch between USB 2 and USB 3 connections. Jochen's suggestion is a significant improvement on the current scheme.
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Do not trust software emulation where you can easily use real hardware...
In most computer there are both USB2 and USB3 port, and it is very easy to get a expansion card for $5 if you happened to work with a PC without USB2...
Skipper: We'll fix it.
Alex: Fix it? How you gonna fix this?
Skipper: Grit, spit and a whole lotta duct tape.
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You may use an "USB 3 sharing switch" (use that search term). They provide connection of an USB device to two or more computers but may be off course also used to connect to two ports of one computer. These usually have a key to switch the ports and may support auto detection.
If you don't want the operator to press the switch key, you may look for one that supports other switching methods. I found at least one that allows switching using a hotkey when connected to a Windows PC. Your test program might then simulate the hotkey activation.
If the switch has an auto detection it should be also possible to trigger that by disabling one of the PC USB ports. But I have done such with Linux only so far and don't know how to do that with Windows. Note that this method (like the one initially asked) requires administrative privileges.
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Hello Jochen
Thank you, that is very helpful. Yours, Leif
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Sir,
I want to execute a windows command in my C++ program.
I know it can be done by adding system function.
I want to add the windows command to a specific drive. I have coded a program which will collect the specific drive and will store the value in a wchar_t store[4]
so in order to go for that specific drive I used
system("store");
command is this correct or wrong?
Thank you
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No that will try to execute a program/script called store. It is not clear what you mean by "add the windows command to a specific drive". Do you mean that you wish to add the drive letter to the command as a parameter, like:
program D:
Please clarify.
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Yes sir store is now carrying the value D:\ I want to execute it by using the variable. What should I do now?
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That still makes no sense, you cannot execute D:\.
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Sir,
I think I have not explained my problem briefly.here is the brief explanation of my problem
I want to find the attributes of the removable drive so, I need to get the string of the drive I've done everything and stored the string value in the "store" variable I mean the variable consists the drive location(D:\) so that I can execute another system function called attrib to find its attributes.
Thank you
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Then it is simply a matter of creating the full command and parameter in a string and passing that string to the system command.
wchar_t sysCommand[128];
swprintf_s(sysCommand, L"attrib %s", store);
system(sysCommand);
See also system, _wsystem[^].
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I have no idea if this is the right answer to the OP's question, Richard, but the fact that you were able to ascertain something from it is impressive. 
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles
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Thanks, it was somewhat easier than many of the questions we are seeing.
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Sir, errors are quiet similar to my initial work.
i.e initially when I use system(store) it shows me an error the same error is showing
when I use system(sysCommand);
Error:
Severity Code Description Project File Line
Error C2664 'int system(const char *)': cannot convert argument 1 from 'wchar_t [128]' to 'const char *' CG C:\Users\User\Desktop\Analyser tools\Sub-Project\Sub-Project\USB informer.cpp 52
Thank you for your kind help
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This is a Unicode issue.
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles
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To sir DavidCrow:
I am using Unicode characet set what should I do now?
I am using only unicode and not multibyte
Thank you for your kind help
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You can't send a wchar_t array to system(). It's expecting a char pointer/array instead.
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles
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Sorry, my mistake, you need to use _wsystem. See the link I provided in a previous message.
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Sir, It works now Thank you for you kind,quick and constant help!
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Sir, I have completed everything and when I run my code the command window disappears immediately what should I do now? Thank you
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The system process will only run the command that you send it, and then terminate. There are alternative ways of doing this: see the exec commands at Process and Environment Control[^].
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