topic Re: Sequence in LabVIEW

Sequence

junim97 — Thu, 30 Oct 2014 12:23:23 GMT

Hello, I have a question about one sequence. I stop my program and I'd like restart where I stopped. How do I do that? Thanks

Re: Sequence

Norbert_B — Thu, 30 Oct 2014 12:31:39 GMT

Please provide more information. What sequence are you talking about? What did you try up til now? What does "stop" mean for you (does it e.g. include a reboot of the system)?

Quite puzzling,

Norbert

Re: Sequence

junim97 — Thu, 30 Oct 2014 12:36:56 GMT

Hello,

Thank you for your help.

I'm sending you my program.

I apreciate if you could take a look.

I have 4 tanks that are always moving the fluid between themself.

For example:

If stop my program between tank 3 and 4, how do I do to the program restart where it stopped?

Re: Sequence

Norbert_B — Thu, 30 Oct 2014 12:43:32 GMT

I am sorry, but i dont see any sequential flow in your application. All i see are five concurrent running loop with a lot of race conditions.

You should start working with a state machine. In this case, you can add a "shutdown" case which saves the last active state to file. An "init" case (which is static first case for execution) loads that file, resets it and proceeds to the next (saved) state for execution.

This will work if init indeed can initialize everything for every case.

Norbert

Re: Sequence

junim97 — Thu, 30 Oct 2014 12:48:17 GMT

Thank you very much.

I will try that :manhappy:

Re: Sequence

Yamaeda — Thu, 30 Oct 2014 15:03:45 GMT

In general, to continue where you quit, you need to save some status to a file which you read back at the start of the program.

Re: Sequence

junim97 — Fri, 31 Oct 2014 15:08:47 GMT

Hi,

I'm sending my program with the flat sequence so you can see what I want to do.

Have the program running and I control the level of the tanks with those numbers controlers. But in my process I'll have pressure transmitters, level sensors and etc instead numbers controlers.

So... If I stop the program when the liquid are moving from tank 3 and tank 4 my EV34 and my B34 have to be on when I restart the program.

Thanks! :manhappy:

Re: Sequence

Norbert_B — Fri, 31 Oct 2014 15:14:12 GMT

A sequence structure is NOT a statemachine. In fact, it makes things even worse compared to your original VI.....

That being said, i urge you to go through the available online material for LV or better to attend a LV class at NI.

Norbert

Re: Sequence

Yamaeda — Fri, 31 Oct 2014 15:39:16 GMT

The absolutely easiest is to combine the values you want to save to a cluster and use Read/Write to binary file.

Then you'll notice that the saved values is of no help as your program writes to the booleans in every loop in every test, so you need to implement some way to jump to your active tank. A State machine comes to mind.

Also your top loop can cause your tanks to run twice, depending on what the values is of Tank4 when you start. That's probably not what you want.

Meh, that snippet became strange ... anyhow, you need to start with something similar to the binary read in the lower right and finish with a similar Write.