Help needed: Memory leak causing system crashing...

Question

Hello guys,
As helped and suggested by Ben and Guenter, I am opening a new post in order to get help from more people here. A little background first...  
We are doing LabView DAQ using a cDAQ9714 module (with AI card 9203 and AO card 9265) at a customer site. We run the excutable on a NI PC (PPC-2115) and had a couples of times (3 so far) that the PC just gone freeze (which is back to normal after a rebooting). After monitor the code running on my own PC for 2 days, I noticed there is a memory leak (memory usage increased 6% after one day run). Now the question is, where the leak is??? 
As a newbee in LabView, I tried to figure it out by myself, but not very sucessful so far. So I think it's probably better to post my code here so you experts can help me with some suggestions. (Ben, I also attached the block diagram in PDF for you) Please forgive me that my code is not written in good manner - I'm not really a trained programmer but more like a self-educated user. I put all the sequence structures in flat as I think this might be easier to read, which makes it quite wide, really wide.
This is the only VI for my program. Basically what I am doing is the following:
1. Initialization of all parameters
2. Read seven 4-20mA current inputs from the 9203 card
3. Process the raw data and calculate the "corrected" values (I used a few formula nodes)
4. Output 7 4-20mA current via 9265 card (then to customer's DCS)
5. Data collection/calculation/outputing are done in a big while loop. I set wait time as 5 secs to save cpu some jucie
6. There is a configuration file I read/save every cycle in case system reboot. Also I do data logging to a file (every 10min by default).
7. Some other small things like local display and stuff.
Again I know my code probably in a mess and hard to read to you guys, but I truely appreciate any comments you provide! Thanks in advance!
Rgds,
Harry
Attachments:
Debug-Harry_0921.vi ‏379 KB
Debug-Harry_0921 BD.pdf ‏842 KB

Answer 1

Well, I'll at least give you points for neatness. However, that is about it.
I didn't really look through all of your logic but I would highly recommend that you check out the examples for implementing state machines. Your application suffers greatly in that once you start you basically jumped off the cliff. There is no way to alter your flow. Once in the sequence structure you MUST execute every frame. If you use a state machine architecture you can take advantage of shift registers and eliminate most of your local variables. You will also be able to stop execution if necessary such as a user abort or an error. Definitely look at using subVIs. Try to avoid implementing most of your program in formula nodes. You have basically written most of your processing there. While formula nodes are easier for very complex equations most of what you have can easily be done in native LabVIEW code. Also if you create subVIs you can iterate over the data sets. You don't need to duplicate the code for every data set.
I tell this to new folks all the time. Take some time to get comfortable with data flow programming. It is a different paradigm than sequential text based languages but once you learn it it is extremely powerful. All your data flow to control execution rather than relying on the sequence frame structure. A state machine will also help quite a bit.
Mark Yedinak
"Does anyone know where the love of God goes when the waves turn the minutes to hours?"
Wreck of the Edmund Fitzgerald - Gordon Lightfoot