How to start/stop 2 parallel while loops

[WhiteCloud]

My question might be simple to answer for experts, but as a Labview beginner would be great to receive your help:

I hav a VI with two parallel while loops. The first loop runs in a tact of 100 ms to aquire voltage, speed and to output a speed setpoint for a motor in the same tact, read from a table.

Finally all values are written to a log-file.

The question: As soon as I run my VI, data logging starts too and my motor runs. How can I implement a button to start all loops parallel, and how can they be parallel be stopped too if I want to stop measurement? Tryed to set a local variable for both stop buttons but it didn´t work.

Thanx to all, Markus

[crossrulz]

Looks to me like you want two FOR loops due to your table.

[Mark_Yedinak]

There are countless threads regarding this topic with lots of examples posted. You may also want to look at the producer/consumer and state machine examples that ship with LabVIEW. Queues and notifiers are good methods for sending data to parallel tasks.

[SnowMule]

Starting the two is easy; use the error cluster to enforce dataflow.

Stopping them is a little trickier; the code you have now isn't very expandable so I'd recommend finding a different architecture.  A notifier functions like a queue with a size of 1, a queue works well for sending commands/data between loops.

[Mark_Yedinak]

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@SnowMule wrote:

Starting the two is easy; use the error cluster to enforce dataflow.

Stopping them is a little trickier; the code you have now isn't very expandable so I'd recommend finding a different architecture.  A notifier functions like a queue with a size of 1, a queue works well for sending commands/data between loops.

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There is one other significant difference between queues and notifiers. A queue can only have one reader. If you have multiple readers of a queue who reads it will be random. A notifier can have multiple listeners. It fact, that is it's purpose.