programing PXI-6509

[norak]

Hi;

I must do a high level function to write/read a DIO PXI-6509 port

I am using NIDAQmx library functions as low level functions.

The question is, what is the better way to do this?

option1:

<pseudocode>

high_level_function()

{

1.DAQmxCreateTask

2.DAQmxCreateDOChan / DAQmxCreateDIChan

3.DAQmxStartTask

4.DAQmxWriteDigitalU8 / DAQmxReadDigitalU8

5.DAQmxStopTask

6.DAQmxClearTask

}

So, in this option everytime you call this function, you have to do all the low level functions

option2:

<pseudocode>

high_level_function_1()

{

1.DAQmxCreateTask

2.DAQmxCreateDOChan / DAQmxCreateDIChan

3.DAQmxStartTask

}

high_level_function_2(taskHandle)

{

1.DAQmxWriteDigitalU8 / DAQmxReadDigitalU8

}

high_level_function_3()

{

1.DAQmxStopTask

2.DAQmxClearTask

} 

So, in this option the task remaind created while the program are running,

and I have tu use global variable (TaskHandle myTaskHandle) because of high_level_function_2 have it as parameter

and I have to use this function in another file.c of the project.

I hope to be enough clear.

any suggestions?

[Colinr]

Norak

I have used option 2 for a silimar requirement.  To limit the scope of the global (and hide all of the excessive overhead that NIDAQmx requires for simple functions) place the functions in a seperate c file  or build the functions into a DLL.  

Option 2 is also my recomendation because it is only a single task that is running continousally the valules on the output ports will remain constant  i do not beleve that the valules written to the port will remain constant when the NIDAQmx task is closed. 

Colin

[norak]

Hi,

thanks for your replay.

I check that if the task finish the DIO set remain in its state...