Hi, i'm having a problem reading the digital input functions from NI-DAQmx in MATLAB (using calllib functions from the DLL).I use the NI USB-6251 BNC device. So, i want to read 4 digital pins (0..3) and stop reading until one of these pins are set HIGH. To do this, i'm going this way: 1. create DI task 2. create DI channel 3. in a while-loop, use the DAQmxReadDigitalU32 function to read the digital values. but that doesn't work. i also tried triggering and timing, but it's always the same thing: I don't get any values (just zeroes), even if all pins have a 5V input. The pvalues1 variable also returns 0, which means that no values have been read. Digital output and analog input/output works fine! Did i make a mistake in the source code? I couldn't find any useful information on the NI homepage or on google about digital input in Matlab or ANSI C. can anybody help me? Thanks! Jan P. Here's my source code: function [ReadHandle, values] = NI_Start_DITask(values)DAQmx_Val_ChanForAllLines = 1;DAQmx_Val_FiniteSamps = 10178;DAQmx_Val_GroupByChannel = 0;DAQmx_Val_ChanPerLine = 0;DAQmx_Val_Rising=int32(10280); DAQmx_Val_Falling=int32(10171);DIPtr=libpointer('uint32Ptr', 0);%int32 DAQmxCreateDIChan (TaskHandle taskHandle, const char lines[], const%char nameToAssignToLines[], int32 lineGrouping);[a,b,DIPtr] = calllib('myni','DAQmxCreateTask','',DIPtr); % create taskDIPtr=libpointer('uint32Ptr',DIPtr);b = calllib('myni','DAQmxCreateDIChan',get(DIPtr,'Value'),'Dev1/port0/line0:3','', ... DAQmx_Val_ChanForAllLines); % create DI channeld = calllib('myni','DAQmxStartTask',DIPtr);ReadHandle = DIPtr; and then in the main function...values = zeros(1,1000);p1=0;vptr=libpointer('uint32Ptr', values);pvalues1 = libpointer('int32Ptr',p1);[ReadHandle, values] = NI_Start_DITask(values); % open function abovepv = libpointer('uint32Ptr', 0);while 1 calllib('myni','DAQmxReadDigitalU32',ReadHandle,10,10,0,values,4000,... pvalues1,0); p1 values if pv.Value==1 break elseif any(values) break end drawnowendNI_stopAndClearTask(ReadHandle);NI_ResetHW('Dev1'); Message Edited by ajn3000 on 12-01-2009 01:37 PMMessage Edited by ajn3000 on 12-01-2009 01:37 PM

Digital I/O

Found the solution, posted in this thread:

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