Global variable reliability

[swap15]

Hello,

I am using a Global variable to transfer data from one VI to other. In one VI, I am writing to the global variable contineously.

And in the second VI, I am reading this global variable and writing it in a text file. Both the processes ( writing to and reading from GV) occur simultaneously. I have tested the software for 24 hours and I had no problems like race condition.

My question is, I have to run this software non-stop for 180 days for permanant monitoring and logging.

I want to know if the Global variable approach is reliable in my case?

regards,

Swap

[Dennis_Knutson]

Your question has nothing to do with multifunction daq. You should have posted to the LabVIEW board.

You would be better off with a producer/consumer design where you pass values to the second loop via a queue. You are liable to either skip values or get duplicate values when you read the global.

[swap15]

sorry, posted here by mistake.........anyways thanks for the reply.

[crossrulz]

Pet peeve of mine.

I inherited a VI much like what you are describing.  It somehow worked on a test system for many many years.  Then there was a computer upgrade and suddenly only 1/4 of the data was logged.  Race conditions.

Luckily, I was already changing that VI to use Queues and then it worked perfectly and didn't burn up the CPU nearly as much.

Look into the Producer/Consumer.  That is what you really need to do.

[swap15]

Hi Crossrulz,

I have never used producer/consumer loop. I have looked into the producer/consumer example but it was to transfer data between two

different loops in the same VI.

In my case, I have two different VI's (not SubVI). Could you please give me an example of how to do it using producer/consumer loop

for two different VI's ?

I would appreciate if you could help me.

Thanks in advance.

regards,

swap

[crossrulz]

You just need to pass the queue reference into your two VIs.