NI-DAQmx function DAQmxGetDeviceAttribute(() returns DAQmxErrorBufferTooSmallForString

[PeteP]

Hi,

We have code that is compiled for use in both 32-bit and 64-bit versions of a program. When running the 32-bit code there is no problem controlling the hardware. When running the 64-bit code the DAQmxErrorBufferTooSmallForString error message is returned in some of the calls to query for the device attributes. The device we are attempting to control is a USB-6259 and the OS is Win 7 x64.

I don't think that this problem is really that the buffer is too small since the same code works fine in the 32-bit version and the buffer is sufficiently large (8K) that there really shouldn't be any possibility for this error to occur.

Below is the complete list of calls that I am making through the NI-DAQmx API.

Best regards and I really hope that someone can figure this out,

Pete

00000000 0.00000000 [840] DAQmxGetSystemInfoAttribute(DAQmx_Sys_DevNames, ["Dev1"]) = DAQmxSuccess 
00000001 0.00035768 [840] DAQmxGetDeviceAttribute("Dev1", DAQmx_Dev_AI_PhysicalChans, [""]) = DAQmxErrorBufferTooSmallForString 
00000002 0.00057210 [840] DAQmxGetDeviceAttribute("Dev1", DAQmx_Dev_AO_PhysicalChans, ["Dev1/ao0, Dev1/ao1, Dev1/ao2, Dev1/ao3"]) = DAQmxSuccess 
00000003 0.00085378 [840] DAQmxGetDeviceAttribute("Dev1", DAQmx_Dev_DO_Lines, ["Dev1/port0/line0, Dev1/port0/line1, Dev1/port0/line2, Dev1/port0/line3, Dev1/port0/line4, Dev1/port0/line5, Dev1/port0/line6, Dev1/port0/line7, Dev1/port0/line8, Dev1/port0/line9, Dev1/port0/line10, Dev1/port0/line11, Dev1/port0/line12, Dev1/port0/line13, Dev1/port0/line14, Dev1/port0/line15, Dev1/port0/line16, Dev1/port0/line17, Dev1/port0/line18, Dev1/port0/line19, Dev1/port0/line20, Dev1/port0/line21, Dev1/port0/line22, Dev1/port0/line23, Dev1/port0/line24, Dev1/port0/line25, Dev1/port0/line26, Dev1/port0/line27, Dev1/port0/line28, Dev1/port0/line29, Dev1/port0/line30, Dev1/port0/line31, Dev1/port1/line0, Dev1/port1/line1, Dev1/port1/line2, Dev1/port1/line3, Dev1/port1/line4, Dev1/port1/line5, Dev1/port1/line6, Dev1/port1/line7, Dev1/port2/line0, Dev1/port2/line1, Dev1/port2/line2, Dev1/port2/line3, Dev1/port2/line4, Dev1/port2/line5, Dev1/port2/line6, Dev1/port2/line7"]) = DAQmxSuccess 
00000004 0.00127711 [840] DAQmxGetDeviceAttribute("Dev1", DAQmx_Dev_DI_Lines, [""]) = DAQmxErrorBufferTooSmallForString 
00000005 0.00146339 [840] DAQmxCreateTask("", ["0000000008D0C320"]) = DAQmxSuccess 
00000006 0.00207268 [840] DAQmxCreateDOChan(0000000008D0C320, "Dev1/port1/line0", NULL, DAQmx_Val_ChanForAllLines) = DAQmxSuccess 
00000007 0.00613461 [840] DAQmxStartTask(0000000008D0C320) = DAQmxSuccess 
00000008 0.00698645 [840] DAQmxWriteDigitalScalarU32(0000000008D0C320, 1, 0, 0, 0000000000000000) = DAQmxSuccess 
00000009 0.00708250 [840] DAQmxStopTask(0000000008D0C320) = DAQmxSuccess 
00000010 0.00732182 [840] DAQmxClearTask(0000000008D0C320) = DAQmxSuccess 
00000011 0.00746703 [840] DAQmxCreateTask("", ["0000000008D0C320"]) = DAQmxSuccess 
00000012 0.00789165 [840] DAQmxCreateDOChan(0000000008D0C320, "Dev1/port1/line1", NULL, DAQmx_Val_ChanForAllLines) = DAQmxSuccess 
00000013 0.01199886 [840] DAQmxStartTask(0000000008D0C320) = DAQmxSuccess 
00000014 0.01285717 [840] DAQmxWriteDigitalScalarU32(0000000008D0C320, 1, 0, 0, 0000000000000000) = DAQmxSuccess 
00000015 0.01294804 [840] DAQmxStopTask(0000000008D0C320) = DAQmxSuccess 
00000016 0.01316892 [840] DAQmxClearTask(0000000008D0C320) = DAQmxSuccess 
00000017 0.01331025 [840] DAQmxCreateTask("", ["0000000008D0C320"]) = DAQmxSuccess 
00000018 0.01373423 [840] DAQmxCreateDOChan(0000000008D0C320, "Dev1/port1/line2", NULL, DAQmx_Val_ChanForAllLines) = DAQmxSuccess 
00000019 0.01762249 [840] DAQmxStartTask(0000000008D0C320) = DAQmxSuccess 
00000020 0.01873176 [840] DAQmxWriteDigitalScalarU32(0000000008D0C320, 1, 0, 0, 0000000000000000) = DAQmxSuccess 
00000021 0.01882231 [840] DAQmxStopTask(0000000008D0C320) = DAQmxSuccess 
00000022 0.01903738 [840] DAQmxClearTask(0000000008D0C320) = DAQmxSuccess 
00000023 0.01917611 [840] DAQmxCreateTask("", ["0000000008D0C320"]) = DAQmxSuccess 
00000024 0.01959945 [840] DAQmxCreateDOChan(0000000008D0C320, "Dev1/port1/line3", NULL, DAQmx_Val_ChanForAllLines) = DAQmxSuccess 
00000025 0.02349773 [840] DAQmxStartTask(0000000008D0C320) = DAQmxSuccess 
00000026 0.02448152 [840] DAQmxWriteDigitalScalarU32(0000000008D0C320, 1, 0, 0, 0000000000000000) = DAQmxSuccess 
00000027 0.02457175 [840] DAQmxStopTask(0000000008D0C320) = DAQmxSuccess 
00000028 0.02478552 [840] DAQmxClearTask(0000000008D0C320) = DAQmxSuccess 
00000029 0.02492394 [840] DAQmxCreateTask("", ["0000000008D0C320"]) = DAQmxSuccess 
00000030 0.02534889 [840] DAQmxCreateDOChan(0000000008D0C320, "Dev1/port1/line4", NULL, DAQmx_Val_ChanForAllLines) = DAQmxSuccess 
00000031 0.02987134 [840] DAQmxStartTask(0000000008D0C320) = DAQmxSuccess 
00000032 0.03087227 [840] DAQmxWriteDigitalScalarU32(0000000008D0C320, 1, 0, 0, 0000000000000000) = DAQmxSuccess 
00000033 0.03099192 [840] DAQmxStopTask(0000000008D0C320) = DAQmxSuccess 
00000034 0.03121378 [840] DAQmxClearTask(0000000008D0C320) = DAQmxSuccess 
00000035 0.03135737 [840] DAQmxCreateTask("", ["0000000008D0C320"]) = DAQmxSuccess 
00000036 0.03180528 [840] DAQmxCreateDOChan(0000000008D0C320, "Dev1/port1/line5", NULL, DAQmx_Val_ChanForAllLines) = DAQmxSuccess 
00000037 0.03584716 [840] DAQmxStartTask(0000000008D0C320) = DAQmxSuccess 
00000038 0.03670255 [840] DAQmxWriteDigitalScalarU32(0000000008D0C320, 1, 0, 0, 0000000000000000) = DAQmxSuccess 
00000039 0.03679440 [840] DAQmxStopTask(0000000008D0C320) = DAQmxSuccess 
00000040 0.03701011 [840] DAQmxClearTask(0000000008D0C320) = DAQmxSuccess 
00000041 0.03715014 [840] DAQmxCreateTask("", ["0000000008D0C320"]) = DAQmxSuccess 
00000042 0.03757671 [840] DAQmxCreateDOChan(0000000008D0C320, "Dev1/port1/line6", NULL, DAQmx_Val_ChanForAllLines) = DAQmxSuccess 
00000043 0.04146950 [840] DAQmxStartTask(0000000008D0C320) = DAQmxSuccess 
00000044 0.04232716 [840] DAQmxWriteDigitalScalarU32(0000000008D0C320, 1, 0, 0, 0000000000000000) = DAQmxSuccess 
00000045 0.04241771 [840] DAQmxStopTask(0000000008D0C320) = DAQmxSuccess 
00000046 0.04263245 [840] DAQmxClearTask(0000000008D0C320) = DAQmxSuccess 
00000047 0.04277249 [840] DAQmxCreateTask("", ["0000000008D0C320"]) = DAQmxSuccess 
00000048 0.04319808 [840] DAQmxCreateDOChan(0000000008D0C320, "Dev1/port1/line7", NULL, DAQmx_Val_ChanForAllLines) = DAQmxSuccess 
00000049 0.04713130 [840] DAQmxStartTask(0000000008D0C320) = DAQmxSuccess 
00000050 0.04820370 [840] DAQmxWriteDigitalScalarU32(0000000008D0C320, 1, 0, 0, 0000000000000000) = DAQmxSuccess 
00000051 0.04829489 [840] DAQmxStopTask(0000000008D0C320) = DAQmxSuccess 
00000052 0.04851254 [840] DAQmxClearTask(0000000008D0C320) = DAQmxSuccess 

[Efrain_G]

Hi Pete,

It is very interesting the fact that your program only errors out when you run it on Win7 x64. As of the function that you are using, the prototype for it is the following:

int32 DAQmxGetDeviceAttribute (const char deviceName[], int32 attribute, void *value, ...);

According to the NI LabWindows CVI Help, you must determine the buffer size needed to allocate the device attributes. If the attribute you pass is a char* or float64*, this parameter is the size of the buffer you pass in. If you pass 0 for this parameter, the function returns the size of the buffer needed to allocate. It might be worthwhile to pass this parameter so that we can find what buffer size is it expecting. It might even be useful if you try to run this program on another Win 7 x64 machine, for the sake of testing.

[PeteP]

Hi Efrain,

It is interesting that the errors only occur on Win7 x64!!! I've changed my code so that it now queries for the buffer size. Here it what happens now:

DAQmxGetSystemInfoAttribute(DAQmx_Sys_DevNames, NULL) = 5
DAQmxGetSystemInfoAttribute(DAQmx_Sys_DevNames, ["Dev1"]) = DAQmxSuccess
DAQmxGetDeviceAttribute("Dev1", DAQmx_Dev_AI_PhysicalChans, NULL) = 341
DAQmxGetDeviceAttribute("Dev1", DAQmx_Dev_AI_PhysicalChans, [""]) = DAQmxErrorBufferTooSmallForString
DAQmxGetDeviceAttribute("Dev1", DAQmx_Dev_AO_PhysicalChans, NULL) = 39
DAQmxGetDeviceAttribute("Dev1", DAQmx_Dev_AO_PhysicalChans, [""]) = DAQmxErrorBufferTooSmallForString
DAQmxGetDeviceAttribute("Dev1", DAQmx_Dev_DO_Lines, NULL) = 885
DAQmxGetDeviceAttribute("Dev1", DAQmx_Dev_DO_Lines, [""]) = DAQmxErrorBufferTooSmallForString
DAQmxGetDeviceAttribute("Dev1", DAQmx_Dev_DI_Lines, NULL) = 885
DAQmxGetDeviceAttribute("Dev1", DAQmx_Dev_DI_Lines, [""]) = DAQmxErrorBufferTooSmallForString

From the buffer sizes it looks like the data is available. We have seen the problem on multiple computers. I am at a loss why no one else has reported this problem. Maybe its an issue with the particular model ("NI-USB 6259") on this particular platform?

As a side note, before I changed my code to query for the buffer size, the call to DAQmxGetSystemInfoAttribute(DAQmx_Sys_DevNames, buffer) would return the buffer size when I passed in a non-null buffer parameter value.

Best regards,

Pete

[Efrain_G]

Hi Pete,

Thank you for the information. It looks like you have suitable buffer sizes from the test you ran. Can you tell me which version of DAQmx do you have installed? We only added Windows 7 64 bit support until we realeased DAQmx 9.0.2.

[PeteP]

Hi Efrain,

I'm using 9.2.2 and I've tried 9.2.3 and I see the same problem there as well.

Best regards,

Pete

[PeteP]

FYI: I have just discovered that if I query using DAQmxGetDeviceAttribute() immediately after it just returned the DAQmxErrorBufferTooSmallForString error then the it succeeds and I have my string.