[RESOLVED] Plotting Real Time Graph

[catherine0136]

Hello. I would like to seek guidance on to do a real time graph.

Currently, my circuit is connected to a power supply and is connected to the computer via a RS232 cable. Voltage level is extracted and the real-time voltage level is plotted (see attached image) and it will keep moving.

But you will realise that there isnt any time shown on the X-axis. I would like to display time in such a way:

Each long marker will represent 1 second and there are 4 long marker, which will represent up to 4 seconds.

When the (5th second) voltage is sense and the real-time voltage is drawn, i would like the new time (5th second) to replace into the 1st marker postion, the (6th second) to replace the 2nd marker position, so on and so forth. The replacement will continue.. ..

As in i would want to have a moving real time. I am currently still doing research on how to do that.

But in the mean time, if anyone of you have any suggestions / guidance on how to do that, i would really appreciate if you can post it.

Thanks in advance!

Attached is also the code on plotting the real-time voltage graph on a picturebox and also the timer coding for reference, if needed.

  'Details of the graph layout 
        Dim Origin As New Point(50, 220)
        Dim xAxisLength As Integer = 210
        Dim yAxisLength As Integer = -250

        If voltsQ.Count > 2 Then
            'Turn the queue into an array:
            Dim voltsQarray As Single() = voltsQ.ToArray

            'Define an array of data points:
            Dim DataPoints(voltsQ.Count - 1) As Point
            Dim x, y As Integer

            'Fill in the array using the voltage readings:
            For i As Integer = 0 To voltsQ.Count - 1
                'Get the volts value from the queue:
                Dim v As Single = voltsQarray(i)
                'Find the distance along the x axis:
                x = Origin.X + CInt(i * xAxisLength / 40)
                'find the height of the data point on the Y axis:

                y = Origin.Y + CInt(v * yAxisLength / maxVolts)
                'Put the point in the array
                DataPoints(i) = New Point(x, y)

            Next
            'Draw the waveform:        
            e.Graphics.DrawCurve(Pens.Green, DataPoints)
        End If

Timer coding:

'read the voltage and get value from RS232 interface
        Call OpenPORT1()

        Single.TryParse(TextBoxVoltage.Text, volts1)
        'add the new reading to the end of the queue
        voltsQ.Enqueue(volts1)

        'remove the old reading at the head of the queue, to keep max. 40 data points    
        If voltsQ.Count > 40 Then voltsQ.Dequeue()

        'update the display with the new data     
        Me.Refresh()

[catherine0136]

Kindly refer to this thread too, if necessary.
This post is related to the url as shown below.

http://www.vbforums.com/showthread.php?t=593254&page=2

[boops boops]

OK, to do this you'll need another Timer and five Labels. You position the labels under the second positions of your graph's x axis. Set the Timer interval to 1000 ms. You'll need a form-level variable for the starting time, and you set it to the current time when you start recording the voltages. At the same time, clear any previous times from the labels (which I'll assume are called Label1 to Label5):

'at form level:
Private StartTime as DateTime
 
'when you start recording:
StartTime = DateTime.Now
Label1.Clear
'... and so on for the other labels.

I'll assume the labels are called Label1 to Label5 positioned from left to right. In the Tick sub of the 1-second timer, you can provide their texts working from right to left like this:

Dim dt As DateTime = DateTime.Now
Dim ts As TimeSpan = dt - StartTime
Label5.Text = ts.Hours.ToString & ":" & ts.Minutes.ToString & ":" & CInt(ts.Seconds).ToString
ts = dt.AddSeconds(1) - StartTime
Label4.Text &= " ;  " & ts.Hours.ToString & ":" & ts.Minutes.ToString & ":" & CInt(ts.Seconds).ToString
ts = dt.AddSeconds(1) - StartTime
'...and so on until you reach Label1.

If there's a more elegant way to turn the TimeSpan into a string, perhaps someone can suggest it.

bye, BB

[MaximilianMayrhofer]

ts.ToString("hh:mm:ss")

[catherine0136]

@MaximilianMayrhofer
Thanks for the suggestion. Will take note of it and try out.

@boops boops
Thanks for your help once again. But i'm not clear regarding the following and need your help to clarify my doubts:

'at form level:
Private StartTime as DateTime 

'when you start recording:
StartTime = DateTime.Now
Label1.Clear'
... and so on for the other labels.

I understand where to declare Private StartTime as DateTime ,
but as for
StartTime = DateTime.Now
Label1.Clear.. ..', i'm kinda lost on where to declare those. =x

[boops boops]

@Catherine. Put it wherever you start recording. If you start recording as soon as you start the program, it could go in the form's Load sub. If you use a button to start and stop recording, it would belong in the button's Click sub.

If you start by connecting the hardware, then there's a problem. I thought I would be able to figure it out from the code you posted but it leaves me mystified. You are reading the voltage value from the text box, and you are getting a plausible-looking output graph. But you do not show anywhere how you get data from the serial port into the text box. How does it get there? That OpenPort1 sub certainly doesn't do anything with volts or TextBox1.Text. Maybe we should go back to the other thread again!

BB

[catherine0136]

Put it wherever you start recording. If you start recording as soon as you start the program, it could go in the form's Load sub. If you use a button to start and stop recording, it would belong in the button's Click sub.

Yesterday afternoon , I think i tried putting at the Form1_Load, but it when i included the Label1.Clear() in it, but it has an error (wriggly green light) under it, something like it is not a member of .. .. i cant rmb, have to go back to school and check later.

If you start by connecting the hardware, then there's a problem. I thought I would be able to figure it out from the code you posted but it leaves me mystified. You are reading the voltage value from the text box, and you are getting a plausible-looking output graph. But you do not show anywhere how you get data from the serial port into the text box. How does it get there? That OpenPort1 sub certainly doesn't do anything with volts or TextBox1.Text. Maybe we should go back to the other thread again!

Anyway, once i connect the hardware and debug the program,
1) the voltage level will be automatically sense
2) and display on the "Voltage Level in Volts" textbox. (It will be a varying voltage).

>> The "Graphical Display" (waveform) is following the voltage shown from the Voltage Level in Volts.(Varying Voltage)

I also have a textbox showing the average voltage[to stabilize the moving needle - the one you help me on].
(But I didnt use your method of Enqueue and dequeue , my supervisor ask me do another method). I stored the voltage levels in seperate textboxes and average it.

The moving needle will actually follow the Average Voltage.

As for the OpenPort1, if i tried replacing it with the suggestion you gave on the another thread: volts = CSng(SerialPort1.ReadByte / 255), or if i change it to Call ReadSerialPort1, it will not work and it also states that this port is close. ><

I hope the explanation for the above is clear. =) If not please inform me and i'll explain it again.

[catherine0136]

@MaximilianMayrhofer :
I used your method, but it states that "Overload resolution failed because no accessible 'ToString' accepts this number of arguments".


@ BB :
I've added everything as shown below. But the timer didnt work the correct way i wanted it to be? Or is it suppose to be this way(but i doubt so).
Im really sorry to trouble you in dealing with my list of questions.

Timer 4 code:

Private Sub Timer4_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer4.Tick

        Dim dt As DateTime = DateTime.Now
        Dim ts As TimeSpan = dt - StartTime

        Label1.Text = ts.Hours.ToString & ":" & ts.Minutes.ToString & ":" & CInt(ts.Seconds).ToString
        ts = dt.AddSeconds(1) - StartTime

        Label2.Text = ts.Hours.ToString & ":" & ts.Minutes.ToString & ":" & CInt(ts.Seconds).ToString
        ts = dt.AddSeconds(1) - StartTime

        Label3.Text = ts.Hours.ToString & ":" & ts.Minutes.ToString & ":" & CInt(ts.Seconds).ToString
        ts = dt.AddSeconds(1) - StartTime

        Label4.Text = ts.Hours.ToString & ":" & ts.Minutes.ToString & ":" & CInt(ts.Seconds).ToString
        ts = dt.AddSeconds(1) - StartTime

        Label5.Text = ts.Hours.ToString & ":" & ts.Minutes.ToString & ":" & CInt(ts.Seconds).ToString
        ts = dt.AddSeconds(1) - StartTime

    End Sub

Private StartTime As DateTime

Form1_Load Code:

StartTime = DateTime.Now

        Label1.Text = ""
        Label2.Text = ""
        Label3.Text = ""
        Label4.Text = ""
        Label5.Text = ""

(I changed the label1.clear() to Label1.text = "" as the method you gave couldnt work.)

When the very first data comes it, (See first image : Solar Cell - Starting)
1) Label1 will start with 0:0:0
2) Label2 , Label3, Label4, Label5 will start with (0:0:1) together at the same time. Is it suppose to work in this way?


Then the next moment: (See attached image - Solar Cell 1 Sec)
1) Label1 will become 0:0:1
2) Label2 , Label3, Label4, Label5 will become (0:0:2) together at the same time.

The next moment:
1) Label 1 will be replaced and become 0:0:2

But I thought label 1 will be 0:0:0, label2 will become 0:0:1, label3 becomes 0:0:2, label4 becomes 0:0:3 , label5 becomes 0:0:4, and label1 will become 0:0:5.. and so forth..Oh dear..

But in the mean time, i'll try my best to figure out another way to solve this problem. =)

[catherine0136]

@jmcilhinney,

I think i understand what u mean.
But as for the code:

MessageBox.Show([date].ToString("HH:mm:ss"))

Hmm.. It will mean that a message box will pop out right? But i believe thats not the way i wanted it to be? But thanks for your suggestion anyway, at least i get to learn something


@BB,
The timer works the way i wanted it to be already
Thank you!!!

[catherine0136]

-removed-

[boops boops]

Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick        
       Call OpenPORT1()
 
'stuff...
 
TextBoxVoltage.Text = Math.Round(Voltage232Index_Dec / 100, 2)
      
'more stuff...

Thanks, that's heart of what I wanted to know. It's nice to see your lab setup too. Now it's clear how the value is read from the serial port in Timer1.Tick. Maybe you realize that those 50 TextBoxes are actually being used as a queue, so in theory you could tidy up the code by putting the readings straight into VoltsQ. Never mind, if it works..

bye, BB

[catherine0136]

@BB
If possible, i'll try to use the VoltsQ, as it'll be much neater and nicer than the way my supervisor suggestions.

[catherine0136]

Hey BB,

Sorry to trouble you again. But i would like you to explain to me regarding the coding shown below, the one regarding the timer that you posted for me. Because i still couldnt understand how to coding works. Especially the coding indicated in (purple).
Once again, sorry to trouble you and thanks for your time.

     Private StartTime As DateTime
   ____________________________________________________
    Private Sub Timer4_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer4.Tick

       Dim dt As DateTime = DateTime.Now       
       Dim ts As TimeSpan = dt - StartTime

        Label1.Text = ts.Hours.ToString & ":" & ts.Minutes.ToString & ":" & CInt(ts.Seconds).ToString
        ts = dt.AddSeconds(1) - StartTime

        Label2.Text = ts.Hours.ToString & ":" & ts.Minutes.ToString & ":" & CInt(ts.Seconds).ToString
        ts = dt.AddSeconds(2) - StartTime

        Label3.Text = ts.Hours.ToString & ":" & ts.Minutes.ToString & ":" & CInt(ts.Seconds).ToString
        ts = dt.AddSeconds(3) - StartTime

        Label4.Text = ts.Hours.ToString & ":" & ts.Minutes.ToString & ":" & CInt(ts.Seconds).ToString
        ts = dt.AddSeconds(4) - StartTime

        Label5.Text = ts.Hours.ToString & ":" & ts.Minutes.ToString & ":" & CInt(ts.Seconds).ToString
        ts = dt.AddSeconds(5) - StartTime

    End Sub
        End Class

And also for the following:

(Dim dt As DateTime = DateTime.Now)

It will mean that (Dim dt) as the actual date and time of the very moment shown on our computer itself?
.

[MaximilianMayrhofer]

Yes. Your system time.

[catherine0136]

Thanks MaximilianMayrhofer! =)

But i still dont really understanding the following, please forgive me as i may be poor in understanding.

For example:

Dim dt As DateTime = DateTime.Now       
 Dim ts As TimeSpan = dt - StartTime

        Label1.Text = ts.Hours.ToString & ":" & ts.Minutes.ToString & ":" & CInt(ts.Seconds).ToString
        ts = dt.AddSeconds(1) - StartTime

So for example, the time now is 4:01:35PM.

Since dt is (DateTime.Now), which is 4:01:35PM,
and ts is (dt-StartTime), so it will mean [ ts = (4:01:35) - StartTime ] correct?

But the StartTime, as in the beginning, 00:00:00 ?

Then for, ts = dt.AddSeconds(1) - StartTime, it will be :
>> ts = 4:01:35.AddSeconds(1) - 00:00:00
which will be:= 4:01:36 - 00:00:00

The above doesnt make sense to me, so I believe my concept towards the above is wrong, therefore i would appreciate if someone could explain to me how it works.

Apologies if the above is unclear. Because i cant really understand how the above subtraction will allow my timer to start from 00:00:00 , 00:00:01, 00:00:02, so on and so forth..

Thanks in advance for the help!
.

[boops boops]

But the StartTime, as in the beginning, 00:00:00 ?

If I remember correctly, there was a point earlier in the program where you had:

StartTime = DateTime.Now

So StartTime contains a snapshot of whatever the system time was at that particular moment. (Hint: if you don't know about using BreakPoints yet, it's a good time to learn it.)

DateTimes and TimeSpans are confusing because they are not like ordinary numbers. If you subtract two Integers you get another Integer as you'd expect:

Dim Lots As Integer = 1000
Dim NotSoMuch As Integer = Lots - 250
TextBox1.Text = NotSoMuch.ToString

and TextBox1 will obligingly show 750. It's exactly like you learned it in algebra. But if you try to subtract two DateTimes, you don't get another DateTime but a TimeSpan instead. You are allowed to use a minus sign for two DateTimes but it has a different meaning to the minus sign used for arithmetic. It's just the way people at Microsoft designed it. And you can't write:

Dim dt As DateTime = DateTime.Now
dt = dt + 5

Instead you have to use AddSeconds or SubtractSeconds. What is more dt.AddSeconds(5) doesn't change the value of dt the way + does with integers. Instead it produces a new DateTime with the required value.

Things like DateTime and TimeSpan are called Reference Types, as opposed to Value Types (like Integers). A String is another example of a reference type, and similarly it has rules of its own for "adding" strings together. You'll get used to them, I hope.

BB

[catherine0136]

@ BB,

Arh, i understand what you meant already!!

Thanks! =)