Hi,
You can use the DAQmxGetErrorString function to get a string representation of the error code.
It can be run directly from the function panel, you do not have to generate the error condition in your application each time you need such a description.
The error code you have given translates to: "Task specified is invalid or does not exist."
You, probably, did not create a task.
You have to create a task, assign channels (digital lines or ports) to it and then start the task before you can make a read operation.
Hope this helps.
S. Eren BALCI
IMESTEK
