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First off, don't assume that a DataReceived event will contain a full message: COM ports aren't packet based - they are character based, and a DataReceived event will fire after each character arrives if necessary.
What you need to do is read each COM port continuously in a separate thread and pass complete messages back to your UI thread for processing / logging / display. The simplest way to handle that would be to use a BackgroundWorker as they have two advantages in this scenario:
1) They provide an easy "status update" mechanism which allows you to ignore Invoke requirements and just pass a whole message back to your UI for display. In a Console app, that means that one task - teh original is responsible for queueing messages for the display, which is good - multiple tasks woudl mean that messages could easily get mixed together instead of separated by lines or similar.
2) They are automatically terminated when the app is: this is not the case with all thread types. This means your in-thread processing can be a lot cleaner as it doesn't have to check for termination at all.
Auto scroll in a console - that's slightly complicated because it's all manual stuff: you'd need to buffer stuff up for display until the "autoscroll hold" is released, and then output the buffer in one long splurt. For a textbox, it's a similar procedure - add items with TextBox.AppendText and it will autoscroll to the end.
Clearing the console is simple: Console.Clear Method (System) | Microsoft Docs[^]
A DGV can be set to use any font you like, just like any other control. I wouldn;t faff with embedding Excel unless you really, really have to!
DGV's aren't slow unless you mistreat them: any control with a lot of data will be sluggish but this may help: Walkthrough: Implement virtual mode in DataGridView control - Windows Forms .NET Framework | Microsoft Docs[^]
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
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OriginalGriff wrote: First off, don't assume that a DataReceived event will contain a full message: COM ports aren't packet based - they are character based, and a DataReceived event will fire after each character arrives if necessary.
I have a Com port logging window (that supports a single Com port) today implemented as a DataGridView and it works reasonably well, it's not the end of the world if a logging message appears in 2 halves in 2 separate rows. What I do think is important is that the time stamps are accurate, that's why I don't want to stay in the event handler too long (the time stamp will be stored first thing in the port_DataReceived event handler). Is it possible make the application to be inside 2 (or more) event handlers (COM1port_DataReceived, COM2port_DataReceived, COM3port_DataReceived, etc) at the same time or will they always be called after each other even if the events happen at the same time?OriginalGriff wrote: add items with TextBox.AppendText and it will autoscroll to the end.
Is the same true for RichTextBox? In that case I guess I can delete RichTextBox off the list.
modified 30-Jan-21 7:33am.
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That's why I wouldn't use the event at all, but put each SerialPort in into own thread, continually monitoring (or perhaps sleeping / checking depending on how accurate you need your timestamps).
That way, your system uses as many cores as it has to receive the data, and you can queue the results into a (lower priority if necessary) UI thread to handle display. The timestamps are a message function, so you assemble that as a package with the whole message, and pass that on. BackgroundWorker is great for that as it includes the UserState object as part of the Progress reporting mechanism which is routed direct to the UI thread.
This ensures independence of your serial ports, and if you have enough cores very low latency for the message / timestamp itself.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
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I'm happy with the solution of using event driven processing, this is a quick-and-dirty piece of software I will need asap (or preferably, yesterday) so I think it's overkill to have separate threads polling SerialPort.BytesToRead. But are you saying that if I create the SerialPort objects in separate threads, then it will be possible for the PC to execute the following events handlers simultaneously: COM1port_DataReceived, COM2port_DataReceived, COM3port_DataReceived, etc?
modified 30-Jan-21 7:34am.
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I have no idea - I've never tried, and I'm really not sure how I would test it ... 
I would doubt it: if all the DataReceived events are set up by the same thread, then the code to kick the actual event off will all be executing on that thread (though the handler itself will be executed on a new thread / pool thread) so there will be some delay introduced there. I also suspect that the actual serial port char received interrupt goes through many layers of software before it even gets to the SerialPort class and then be routed to the right thread to kick of the Event.
When I need multiple sources, I prefer to use separate threads and poll instead of use Events as it's rather more "immediate".
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
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OriginalGriff wrote: I would doubt it: if all the DataReceived events are set up by the same thread
No, I wouldn't do that, I would create my SerialPort objects and hook up the DataReceived events in separate threads.
modified 30-Jan-21 8:10am.
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That's just adding a further layer of abstraction - the DataReceived event is fired on a pool thread, not the original starter thread, so ... 
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
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So you're saying it's not a good idea? How many pool threads does a PC have? Can I somehow dictate what pool thread the different Com ports should issue events onto?
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arnold_w wrote: How many pool threads does a PC have?
Depends: Thread Pools - Win32 apps | Microsoft Docs[^]
arnold_w wrote: Can I somehow dictate what pool thread the different Com ports should issue events onto?
No. It's a pool. As an when a thread is needed, one is pulled from the pool and started.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
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I need to peel potatoes but I don't want to use a potato peeler.
It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it.
― Confucian Analects: Rules of Confucius about his food
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You haven't got a swiss army knife?
Software rusts. Simon Stephenson, ca 1994. So does this signature. me, 2012
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I do! ... But I don't want to use it because it might do the job. 
It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it.
― Confucian Analects: Rules of Confucius about his food
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A Serialport as a part of the UI - so Threading isn't a good idea. But you can also work with the DataReceived-Event from the/each port. Why do you want to use Threading or a Backgroundworker for this approach ?
Do you have considered that there are other Control than a Textbox ? For example a ListView ... But you should realize that each and every list has an End ... so an endless Form isn't really possible to realize.
If you want to write to an Excel-Sheet it isn't necessary to know something about VBA - this work could be done complete inside your Application.
What problem do you have with a DataGridView ? But I think it isn't the right approach (! glass-bowl  )
RichTextBox could also be a good idea ...
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SerialPort isn't a UI control: it can be dropped on a form if you must, but it doesn't have any display component (that's why it appears at the bottom, off the form like a Timer control does).
You can - and should - access it from a thread other than the UI: indeed the DataReceived event is never fired on the UI thread anyway!
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
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Ralf Meier wrote: Why do you want to use Threading or a Backgroundworker for this approach ?
Let's assume updating the GUI component with an extra row takes 10 ms, but queueing a task takes 1 ms. Then, if I don't queue the task, the event handler will be blocked for 10 ms for each packet, but if I queue a task instead then my event handler will only block for 1 ms. Of course, with the latter approach my data will show up with a slight delay in the GUI component, but that's acceptable.Ralf Meier wrote: For example a ListView
I've never used a ListView. Would it be a better choice than RichTextBox and DataGridView, in your opinion?Ralf Meier wrote: But you should realize that each and every list has an End
That's fine, I don't have infinite RAM in my computer anyways, but for sure 65535 characters is too little. Ralf Meier wrote: If you want to write to an Excel-Sheet it isn't necessary to know something about VBA - this work could be done complete inside your Application.
But how do I know which row I should add the latest data to, without running a for-loop to find the first empty row? RichTextBox and DataGridBox have append methods that will figure out where the end is for you.Ralf Meier wrote: What problem do you have with a DataGridView ?
Today I have a logging window (that supports a single Com port) implemented as DataGridview and it seems to be lagging a lot, but I guess I must be doing something wrong. Also, I had to implement my own copy-to-clipboard function and I had some problems with it because every once in a while (e.g. during boot-up and power down) there would come strange characters from my device and if a null-character was present in the middle, then only half the text would appear in the clipboard, so I had to spend time making a workaround for that. With e.g. RichTextBox, I wouldn't have to do this.
modified 30-Jan-21 7:04am.
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Hi,
here are my suggestions:
1.
use a single BackGroundWorker per COM port; use its progress reporting facility to report displayable results.
2.
Use synchronous read operations, thus avoiding the tricky DataReceived event.
If you are lucky and the peripheral reports text messages ending on some specific terminator, use ReadLine(); when necessary, adjust the NewLine property to equal that terminator. If not, just use Read and have the BGW discover the beginning and end of every message.
3.
For the UI use the simplest List oriented Control that satisfies your interactive requirements; a ListView is good, however I prefer a ListBox.
4.
Define a little class holding the raw data of one displayable result. That is one object, no more expensive than the array a ListView would need. Instances of this class, not strings, are to be added to the ListBox Items collection.
5.
Make the ListBox ownerdrawn, giving it a fixed ItemHeight, and an appropriate DrawItem handler that takes care of horizontal positioning, coloring, and whatever fancy styling you may want.
That's it; and it is bound to be simpler than the code you probably are experementing with right now...
Luc Pattyn [My Articles]
If you can't find it on YouTube try TikTok...
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I want to call SaveChanges in my WPF app. SaveChanges calls AddCompany or UpdateCompany on the server, I DON'T want the UI to hang up. After the save completes, there are other things I need to do.
public override bool SaveChanges()
{
bool isValid = Validate();
if (isValid)
{
var task = Task.Factory.StartNew(() =>
{
if (Company.Id == 0)
{
AppCore.BizObject.AddCompany(Company);
}
else
{
AppCore.BizObject.UpdateCompany(Company);
}
}).ContinueWith(a =>
{
});
}
return isValid;
}
This is being called from a Save button. This doesn't feel right. What's the right way to call AddCompany/UpdateCompany asynchronously and then handle the clean up stuff? I'm not sure how to structure the code.
Thanks
If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.
modified 27-Jan-21 12:49pm.
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Move it to a second thread: I'd suggest a BackgroundWorker as a simple to manage way to do it - it can report progress and completion via Events
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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Doesn't that negate the whole purpose of Async/Await?
What I'm trying to understand is the correct way to use Async/Await.
If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.
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As already mentioned by OriginalGriff the correct way would be using a worker thread
modified 28-Jan-21 4:34am.
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For such an aggressive use of bold there, it's amusing that you called out the wrong person. Kevin Marois is the person who asked the question.
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Sorry! the fast copy/paste operations may not always be 100% correct! 
PS: I have edited my post.
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I'm with you. BGW is underappreciated and often misunderstood; particularly the "reporting" part (object state versus the pseudo "% complete").
It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it.
― Confucian Analects: Rules of Confucius about his food
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The method you're overriding doesn't return a Task (or ValueTask), so you can't make the override an async method.
You would need to make the method in the base class return either Task<bool> or ValueTask<bool>. The calling method would then need to wait for the returned task to complete before proceeding, either using await or ContinueWith.
It's also not helped by the fact that the methods you want to call on a background thread are synchronous methods. It would be better if they were async as well, so you could avoid explicitly spinning up a new Task to run them off-UI.
public override ValueTask<bool> SaveChanges()
{
bool isValid = Validate();
if (isValid)
{
var task = Company.Id == 0
? Task.Run(() => AppCore.BizObject.AddCompany(Company))
: Task.Run(() => AppCore.BizObject.UpdateCompany(Company));
await task;
}
return isValid;
} Understanding the Whys, Whats, and Whens of ValueTask | .NET Blog[^]
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Thank you!
If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.
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