crossrulz

I often have to send a lot of data with a CRC over a serial port. I have my data stored as a byte array (to do the CRC calculation) and then use the Byte Array to String to then send out to the serial port. This primitive does not convert to an ASCII equivalent. Our standard here is to send a 0x02 at the beginning of each serial message as a synch byte and I have had no problems with this method. But if you are only sending 1 byte, this method would not be very good for you. ShaunR probably has the best solution for you.

QUOTE For as long as I have been using LV, NI keeps telling everybody NOT to use locals...beaten into our heads sometimes. So I then see all of my coworkers using the property nodes instead. Then I tell them why that is even worse. NI tells people not to use the locals because it breaks off from the data flow paradigm and is likely to create race conditions. Guess what...setting the value with property nodes does the exact same thing except that it is WAY slower. I have some test data floating around somewhere that proves this. So now I'm getting everybody to use shift registers inside of their loops instead of the locals and/or property nodes to save data inside the loop. It was almost funny when I compared my CRC program (using shift registers) to coworker's (using property nodes to set front panel objects being used as temperary variables) and mine ran circles around his and he was so perplexed.

The problem is that if you want three threads to run in parallel, they need to be in separate loops. If you are keeping your UI to two or three VIs, the following will be fine. Setup different while loops just like what you already have with the event structure, but have each event structure check for a different button (ie. one event structure to check Test 1, another for Test 2, and a third for Test 3 per Michael's example). If you go to more than two or three VIs, then dynamically calling would probably be best.

This sounds familiar. Check out this recent post for some good ideas. The most likely is that you are missing the VISA drivers on the second computer. http://forums.lavag.org/Installing-stand-a...0653#entry60653

vugie and ned beat me to it, but I was gonna say that this sounds just like the quick drop that was introduced in LV8.6. I haven't used the tool much yet, mostly from habbit of all the clicking around with the menu. I'll have to experiment more.

QUOTE (Tim_S @ Mar 19 2009, 08:56 AM) GVA - Global Variable Anonymous. I like it. I have somehow been global free for 3 years. But are functional globals just a crutch or are they actually better to use? Hmm...

Cat, I'm with SULLutions when it comes to the LV2 global variable. His VI is too old for me to read (in 5.1, I am now down to only 8.6), but I made a VI with similar functionality. I saved it in LV8.0, so hopefully everybody can read it. Download File:post-11268-1237404447.vi But still, don't feel bad for using a global variable. They are there for a reason, and I think this was one of them. SULLutions, Can you repost a newer version of your abort vi? I'd just like to see how you handled it.

The LV Intermediate I course has a really good example of this using Queues.

I would just put the terminal of the boolean inside the "Value Change" event. That is the only one you should ever care about resetting the boolean. None of the other events should care about the state of the boolean. Now if you are using mulitple event structures, the changed value event will register for all event structures with that "Value Change" event. Therefore, it doesn't matter which event structure you put the terminal in. As soon as that terminal is read, the latch will reset. For instance, in the picture below, when the stop button is pressed both event structures will tell their respective while loops to stop. The top loop will reset the latch value of the stop button.

I even went as far as creating a VI that I put in my user library. I use this one all the time. This VI is in LV 8.6

You can download drivers from the NI website. Try this link for your HP8110. If you don't like these, then you need to lookup the SCPI commands and create VIs that will build up the commands and send them over the GPIB bus.

OpenG has a good wait function that uses an Occurance if you'd rather not code it up yourself. I'd say the event structure would be the next easiest way to go.

I did something similar when I first downloaded LV8.6. Quite frankly, I agree that the cleanup tool actually made my VIs look worse. Then again, I try to make my code look really clean in the first place. I think the real problem is that you can't really set concrete rules when it comes to LV code. Sometimes you have to give on one rule for the sake of readability and/or performance. So I simply just ignore that feature. Though, I have some real BAD speghetti code that I inherited. I should try it sometime. As a side note, the only new feature I like in 8.6 is being able to alter the properties of multiple objects at once. That will save me hours of work in the near future.

schneidley, I think this will work for you. I used two shared variables to start and stop the two parallel processes. You could also use globals. Just make sure you initialize these variables very first thing in your program. If you are passing read data between the two processes, I would highly recommend using queues.

QUOTE (Brian B @ Jul 24 2008, 01:02 PM) Sorry. I should have looked at what versions you had. I just did a save for version 8.0.

Your problem (at least in this example) is that the global variable is only being written to immediately coming into the loop. The loop is then dominated by the subVI. Therefore the global to exit the subVI will never be written to again. The following recommendation is only for GUI stop commands, but it might lead to other ideas for your specific situation. Use another loop with an Event Structure in it. Set an event to "Stop" value changing and then write the new value to the global variable. This will then end the subVI. As long as you don't have a Timeout event case, the event structure uses no cpu cycles until a registered event happens, so performance issues are nonexistant. My edited code for the top level VI is attached.

If I set up Data Binding on an indicator to a network shared variable, how often is the indicator updated? I am using LV 8.5 with the RT module. I am trying to get updates from the RT target to show up on the Windows computer. I would prefer not to constantly poll the shared variables if possible. We don't have the DSC module, so I can't use event structures to update that way. What I am hoping is that the data binding updates is event driven and therefore making it a lot more efficient than the polling I am currently doing.