C#•9mo ago

Run code cyclical

Can anyone help me with running code cyclical? I have code that I want to execute every 10ms or 1 sec etc. And not just from an event, it needs to keep updating the code. Or just every cycle time I am mainly a PLC-programmer, don't know if C# also works with cyclic code execution the same as I am used to. C# 7.0, .NET Maui for android and windows

40 Replies

Pobiega•9mo ago

It doesn't work like a PLC at all. However, it is of course doable. The modern way to do this would probably be with a PeriodicTimer

doolhofxOP•9mo ago

I thought to already indeed Thanks I will search for it!

Pobiega•9mo ago

I don't know MAUI at all, so I don't know know how they prefer running background jobs, but the "normal" approach would be via a IHostedService (like BackgroundService, or make your own).

doolhofxOP•9mo ago

How do you mean that? Sorry I am a total ammateur in C#. Code that runs in the background?

doolhofxOP•9mo ago

https://www.youtube.com/watch?v=N7vhJ7O56iM&ab_channel=IAmTimCorey I am now following this video. But where do I place my code that is now inside the btn Clicked event? Just in the MainPage() ?

IAmTimCorey

YouTube

Periodic Timer in C# Including .NET 8 Updates

The PeriodicTimer allows us to run tasks on a timer in a way that is efficient and asynchronous. Instead of using the threading timer, a UI timer, or a DispatcherTimer and depending on callbacks, we can use this one timer to safely execute our code. Let's see how they work in this 10-minute training video. Full Training Courses: https://IAmTimC...

Pobiega•9mo ago

Why on earth are you doing MAUI if you are a beginner? O_O Its by far the most complicated project type with thousands of gotchas and problems.

doolhofxOP•9mo ago

Oh oops

Pobiega•9mo ago

However, thats sort of a side issue You are mentioning a click event, so how would this "cyclic" code execution interact with the button? does the button start it? if so, when does it stop?

doolhofxOP•9mo ago

I can programm, I know how the syntax and all works. And I can create a good console application but this with UI and so is totally new

Pobiega•9mo ago

what about threading?

doolhofxOP•9mo ago

Not, the button is removed and the code just needs to run

Pobiega•9mo ago

so it runs forever after the button is clicked? or is there no need for a button at all?

doolhofxOP•9mo ago

No button Just run the code over and over again

Pobiega•9mo ago

alright

doolhofxOP•9mo ago

I want a constant flow of data from my PLC --> application

Pobiega•9mo ago

right. Well, the problem you need to solve is how do we run this periodictimer without blocking the main UI thread we want the rest of the app to work as is while this works thats most often called "a background job"

doolhofxOP•9mo ago

Ooh yea that's with threading, right? multithreading

Pobiega•9mo ago

yeah, essentially but manually multithreading is hard and easy to get wrong luckily, .NET has a bunch of tools to help

doolhofxOP•9mo ago

nice!

Pobiega•9mo ago

again, I don't know MAUI. at all.

doolhofxOP•9mo ago

No problem, I think if I know the direction I have to goto I can figure it out

Pobiega•9mo ago

but in a console app, or a web api, or pretty much any other project type, you'd use the https://learn.microsoft.com/en-us/dotnet/core/extensions/generic-host?tabs=appbuilder and add your background job as a new hosted service but this kinda requires that you know and understand dependency injection and you'll likely want a messenger like MediatR or Immediate.Handlers to send messages from your job into your "main app"

doolhofxOP•9mo ago

I get it yes So it's not quite easy

Pobiega•9mo ago

not to do it well there are ways to do it "dirty" that are much simpler you certainly could just start a new thread and ask it to run your "cyclic" method that never returns

doolhofxOP•9mo ago

Isn't that enough? Or can those cause a lot of issues?

Pobiega•9mo ago

thats... fine. again dunno about MAUI, but in other GUI apps there is some complications about updating the GUI from the non-main thread

doolhofxOP•9mo ago

Can I send you a private message and give some more project background information? Maybe you know a total different way to achieve what I want? That is way more simpel haha

Pobiega•9mo ago

No thanks. Help here is done in public, not in private 🙂

doolhofxOP•9mo ago

Oke, no problem I understand it Uuh yea I got a PLC that also is a Modbus TCP slave (Server). I want to read data from that slave, so I have programmed a Modbus Master (client) in C# maui that works fine, but depends on the button click to read and write data from the PLC (slave). Now making it read/write every, for example, 1 second makes it easier to have a live view of what is happening

Pobiega•9mo ago

yeah I understand

doolhofxOP•9mo ago

Got it working now, don't know how clean it is but well.

private async void brnReadHolding_Clicked(object sender, EventArgs e)
    {
        using PeriodicTimer timer = 
new(TimeSpan.FromMilliseconds(1000));
                while (await timer.WaitForNextTickAsync())
                {
                    //Code to execute
                }

private async void brnReadHolding_Clicked(object sender, EventArgs e)
    {
        using PeriodicTimer timer = 
new(TimeSpan.FromMilliseconds(1000));
                while (await timer.WaitForNextTickAsync())
                {
                    //Code to execute
                }

Pobiega•9mo ago

thats indeed how you use a periodic timer but its still in a button click, and its an async void I guess being FNF isnt a huge problem for your app thou

doolhofxOP•9mo ago

I know, haha. Probably not super clean what is FNF?

Pobiega•9mo ago

fire 'n forget

doolhofxOP•9mo ago

Yea I guess so. Maybe I look into ending it with pressing the button again

Pobiega•9mo ago

that is actually fairly easy to do

doolhofxOP•9mo ago

You are probably laughing at my program but for a first Maui project I am actually glad how it is already as a start

Pobiega•9mo ago

to easily cancel your timer gracefully, I recommend using a CancellationToken + CancellationTokenSource the basic idea is you just pass in a token object into your timer.WaitForNextTickAsync(cancellationToken) and then when that token is triggered by the CTSource, the timer function till return return false and thus stop

doolhofxOP•9mo ago

Oke, thanks I will try it

Pobiega•9mo ago

you'd need to move your timer stuff to a separate method and add some state to know if its already running or not

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Run code cyclical