I am writing a program which works if... Or works not if... - see the next lines... 🙂 ... The program has one part, mainly GUI- and User-Interaction. The other part is a DLL. In the DLL there are readouts over RS232 from a external controller-board. Sometimes the controller-board needs some time (known how much) and this time must pass by then the result can be read out from the controller board ... and so on ... By not blocking the GUI-User-Program for waiting the return-value of the the DLL-functions (which need some seconds to be finished) I start in the DLL a thread with CmtScheduleThreadPoolFunction(DEFAULT_THREAD_POOL_HANDLE, THREAD_FunctionX, &tmpTFP, NULL); with "tmpTFP" as a type-instance of "TYPE_THREAD_FUNCTION_PARAMETERS": typedef struct{ // int IntVal1; // 1. Integer-Wert int IntVal2; // 2. Integer-Wert int IntVal3; // 3. Integer-Wert int IntVal4; // 4. Integer-Wert int IntVal5; // 5. Integer-Wert // int IntBuffer1[32]; // 1. Integer-Buffer (aktuell genügt einer) // double DblVal1; // 1. Double-Wert double DblVal2; // 2. Double-Wert double DblVal3; // 3. Double-Wert double DblVal4; // 4. Double-Wert double DblVal5; // 5. Double-Wert // char CharVal1; // 1. (Einzel-)Char-Wert char CharVal2; // 2. (Einzel-)Char-Wert char CharVal3; // 3. (Einzel-)Char-Wert char CharVal4; // 4. (Einzel-)Char-Wert char CharVal5; // 5. (Einzel-)Char-Wert // char CharBuffer1[1024]; // 1. Char-Buffer (akutell genügt einer) //} TYPE_THREAD_FUNCTION_PARAMETERS; In the GUI-User-Program I get quick a default-return-value of the thread-starting function. Then I poll the DLL (some global state-variables are used for that) when it is finished. Depending on the contacted (RS232) controller-board the waiting time depends on the "mood" of the controller-board. In the DLL-polling-routine of the GUI-User-Program now everything is working fine - without using "SetCtrlVal" ! In my GUI there is a info/comment text-box for messages. If I make some User-Outputs by using "SetCtrlVal" I get always errors, caused by wrong "TYPE_THREAD_FUNCTION_PARAMETERS"-values in the thread-function. If I set a break-point at the thread-function start I see mostly false values in my transfer-structure-variables. If I set a break-point at the thread-function-caller "CmtScheduleThreadPoolFunction(...)" and at the beginning of the thread the values are (mostly) correct! I tried many and different things - but: If I ONLY (!) commenting out the one (!) line with "SetCtrlVal" the program works, all states are polled well out of the DLL. If I replace the "SetCtrlVal" with a own written logging-file function everything works fine and after the program finished I can watch the log-file and see all user-info's. BUT with "SetCtrlVal" instead or together or (...) it does not work. Maybe my description is not totaly clear, but believe me: ONLY ONE line - the "SetCtrlVal"-line - must be comented out to let the program work fine! Because if the "SetCtrlVal"-line is in GUI-User-program, after the thread-call in the DLL, the DLL-Memory seems to be corrupted by the "SetCtrlVal"-Call in the GUI-User-program. Best regards, F.

...by the way: I talked with a "visual studio programmer" about the destruction of the thread-parameter pointer in LabWindows/CVI and he was very surprised about that and he said he also would expect that the to the thread given parameter pointer and it's memory would exist as long as that thread is runing... now I am not longer surprised about that, because my original expectation about that pointer/memory is not "unusual" or "unapologetic". Greetings, F.

There may be a problem in your structure depending on where your variable is defined. You said that after you pass the address of the variable to the thread function the caller one terminates. Now, as you can read in the help every value passed in threadFunctionData parameter of the spawned function must point to a memory area that persist when the fuction is in execution: if your variable is defined at function-level it will not be valid when the thread executes since the caller has terminated and released its local memory. Your approach with a global variable is a valid alternative, but whichever is the solution you find data passed to the thread function must be valid throughout its life.

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