Error -10609 occured at AI Control

[Timothy]

Recently we have been getting the following error message when trying to run 5 of our programs all at once.

"Error -10609 occured at AI Control

NI-DAQLV: A transfer is already in progress for the
specific resource, or the operation is not allowed
because the device is in the process of performing
transfers, possibly with different resources."

I believe that this error is coming from the AI Control.vi which is on of the subVIs of AI aquire waveform.vi. We have been using the AI aquire waveform.vi to read our thermocouples from the DAQ board and in the past have had no problems running multiple programs (with multiple thermocouples) using LabVIEW 6.0. When we switched to using the Executables that we created using LabVIEW
6.1 on another computer we started running into this problem. The development computer is a sony VAIO 1.6GHz P4 with 128 MB Ram, the operating computer is a Dell OptiPlex P1 of unknown processor speed with 64 MB of Ram.

If you have any ideas on how to fix this problem I would greatly appreciate it. Also, we are running the NI-DAQ 6.3.9 version and a PCI-MIO-16E-4 DAQ board.

[Filipe A.]

Hello;

The NI-DAQ driver is not a multithreaded driver, meaning that in case you have more than one request, at the same time, for the same resource, you might get an error.

In case you need 5 different tasks running at the same time, the best way to do that is to combine all 5 tasks on the same code.

Regards
Filipe A.
Applications Engineer
National Instruments

[Timothy]

Filipe,

Thank you for your response. One of NI's field engineers contacted me about this problem and I think that we have it solved. I am now using the Semaphore commands to control access to the DAQ board so that only one program can access it at one time.

Thank you for your help. If I can figure out how to add all tasks to one code then I will try that. The current problem with that is that not all tasks are always needed.

Thank you,

Timothy