Rhys,
I think that loop will stop, once you let it run. The three Dequeue Element functions in the Logging Control = True case all have infinite timeouts. Thus, that case will not complte execution until something has been placed into EACH of the queues. If either the Thermocopule Task or the Voltage Task is not running, the logging loop will not complete its iteration. Furthermore, the Quit Test local variable is probably read at the very beginning of each iteration. If the Quit Test button is pressed after that, an additional iteration of the loop will be required, meaning that it will wait for each of the queues to get an addtional element. If any of the enqueuing loop has already stopped (which is likely), The logging loop will wait forever. The shutdown on error from releasing the queue will not work either because the error values tested in the logging loop are the errors generated by the Obtain Queue functions. In this situation those will almost certainly be No Error.
Other problems:
1. Block diagram is too large. Style Guides recommend that the blcok diagram not exceed the size of one screen.
2. Stacked Sequence structures should not be used. They obscure code, cause right to left wiring, and are very difficult to modify and troubleshoot. They probably cause execution to be more sequential than is actually required.
3. Avoid the use of local variables. They break dataflow, are prone to race conditions, create extra data copies, force the code to run in the UI thread, and are slower than most other ways of transferring data. Local variables are not like locals in text-based languages. They are really remote terminals for front panel controls and indicators. For all practical purposes in LabVIEW the wire is the variable.
4. If you want to use the Queue release error to terminate a loop, you must put the error wires on shift registers. This is an accepted practice, although I, personally, do not like it.
Suggestions. First. Learn about dataflow.
Next. Consider switching to a Producer/Consumer plus State Machine architecture for your program. This would allow you to eliminate the sequence structure, the local variables, and probably some of the loops. It would give you a robust and scalable program architecture.
Also. Learn to use subVIs. Your Strain, Thermocouple, and Voltage tasks use identical code. The only differences are the values of the DAQmx Tasks, the enable booleans, and the queue names. By writing one subVI with these as inputs you simplfy your block diagram. The subVI can be tested without needing the whole program to work. And if you ever need to change the functionality, you only need to change it one place.
The front panel looks very nice.
Lynn
