LabVIEW
while loop next iteration inside producer consumer
Solved!
Hi jK,
What do you think is the problem ?
The problem is you are waiting for a value change event of an indicator "data". Indicators will NEVER create valuechange events (unless you use a special property node)!
and what is the solution?
You should wait for your user-defined event instead…
Hi jengkamK20,
Looking at your VI, despite the helpful comments, it's really not clear which loop is really the consumer!
Your producer labelled loop reads the data (presumably this array + 100ms wait simulates a 10Hz data source) and then you want to send it to the 'data' indicator, is this right?
The consumer doesn't consume the data. Instead, it seems to be just passing it back to the producer, which has to then both produce and consume! It's not surprising that the loop is difficult to work out.
If you want to use a Queue with the producer (this is the normal P/C Data structure) then don't make the enqueuing of data conditionally depend on the execution of the Event Structure. In the top producer loop, if the Event Structure doesn't trigger, then the loop iteration never finishes (as you're seeing). If you remove the Event Structure then the loop will enqueue an element with no problem. Then, the consumer can dequeue the element and place it in the 'data' indicator.
Alternatively, if you want to use User Events, then you need to be clear about where you want data to start, go to, be processed and so on. If the producer generates the data and you want to handle it based on the event, you should generate an event when the data is 'produced' - perhaps by placing a Generate Event node outside of the Event Structure. Then, changing the Event Case to be the dynamic user event will work (and you can keep your data indicator in the event structure). Note, that in this case, your consumer isn't involved at all (and further, you're making a very convoluted setup that could be replaced by a simple wire...)
It's pretty likely that this is a test VI to check how things work, or to explore the tools available in LabVIEW, so something being convoluted is fine if you know how you want to use it in future. Just make sure you know what you want to happen where!
Edit: I attached a VI which compares Queues with Events. Neither of the cases I show uses both, although you can if you want/need to.
