50103 error

[Tim 152]

Any ideas on fixin this app? I keep gettin a 5103 error. Apparently the tasks are not clearing right or since I have multiple tasks they are interfering.

[gcs]

It appears that this VI attempts to runs two tasks that use the AI engine of the same device at the same time. At any time, only one task can reserve the AI engine on a device. Since these two tasks have the same timing specification, it should be easy to combine them into a single task.

geoff

[Sean_C.]

Hello Tim,

Thank you for contacting National Instruments.

You are getting this error because you trying to perform two separate Analog Input (AI) tasks on the same device at the same time. This is why you are getting the "The specified resource is reserved" error.

To acquire multiple channels simultaneously, you should acquire multiple channels in the same task. To acquire from ai1 and ai2 on Dev1, simply type "Dev1/ai1:2" in the Input Physical Channel control. Please see the following Knowledge Base for more information: http://digital.ni.com/public.nsf/3efedde4322fef19862567740067f3cc/04bedd9e9e91ed3486256d180048116d?OpenDocument .

Please let me know if you have any further questions.

Sincerely,
Sean C.
Applications Engineer
National Instruments

[Tim 152]

Thanks Sean,
Ill have to take you up cause i do have another question for yah. I dont understand why it is so difficult to pass data from one loop to another while they are running. I have an app that runs all the time with a temperature readout on AI1. This is part of a while loop executing @ 4 hertz. I have another PID loop amidst some case structure that I want to be able to activate at any given time and run. The problem for one is that the input for this PID loop and the head readout use the same AI1 temp input. So I get an error if I run them together. It would be nice if I could have the temp data from the outside pass its info into the PID loop (Temp is my process variable). Then I could still have my temp display on all the time, but when I want to turn on my PID loop it is also receiving the temp.
Thanks
Tim

[Tim 152]

I figured this ish out about the inputs. I just made my own instead of using the wizard thingy, but I still dont understand why it is so hard to pass data between loops between iterations.

[Sean_C.]

Hi Tim,

Without seeing your VI, it's hard for me to offer a solution, but I think I have a basic idea of your problem. Because of data flow programming, the method of execution in LabVIEW, a while loop will not execute until all inputs to that while loop are available. Similarly, data will not be released from the while loop until that loop has finished execution. What this means is that you cannot pass data between loops with wires. To pass data between loops while they are executing, you can use local variables. These allow you to read the value of a control or indicator from multiple places on your block diagram at the same time. I am attaching a very simple example in which one stop button stops the execution of two parallel loops by way of a local variable.

I hope this helps!

Sean C.
Applications Engineer
National Instruments