DAQmx Start Task.vi:7220004 Error in multi-sub

[Alisterio]

Hi Reader,

I am new to the NI forums, so if my question is not in the best format, please let me know what i should say so that it conforms to forums guidelines.

This might be hard to explain, but I am trying to figure out where the error comes out from here. This code does interface with hardware (a NI USB-6229) and I am running a signal generator and two photodiodes.  In terms of order, I will go from top to bottom, photodiode, photodiode, and signal generator. I assume this would make it difficult for people to actually test this code. So I will do my best to explain what I am doing. 

The middle channel is creating the error.

Essentially, I am trying to turn on two photodiodes and a signal generator simultaneously. I am starting them at the same time, running them hopefully at the same time, and stopping them at the same time. I have ensured that the analog input ports are different for the two photodiodes I am using. I am not entirely sure whether I can use the same clock. If anyone needs more information I am very willing to put up more. 

Note that Main Code is where SO_GetPltrace is located (the sub_VI of the while loop). The error is from SO_GetPLtrace.

Cheers,

Alistrio

[RavensFan · Accepted solution]

Did you try searching for "Error 50103" in the forums or on Google?

If you had, you'd have already come across 100's to 1000's of hits telling you what the problem is.  You can't have multiple tasks on the same device.

You need to combine your multiple channels into a single task!

[Alisterio]

Thank you so much! I apologise for my ignorance. When I looked this problem up, I was not aware that the numbers were actually problem-specific. I just chucked the entire error message but got no hits on Google search that had my specific issue. I will be more meticulous in the future. Thank you for the massive tip. 

Though just as a clarification, why is it that I could have two start tasks but not three? I assume that's because I am trying to get my DAQ to start twice? The two start tasks I originally had does interface with different devices. The signal generator does not pass through the USB-6229 DAQ whilst the photodiodes do. Well I think that makes sense to me I am just outlining this as well in case someone else is wondering. Thanks again.