I am new to coding. I have been asked to write a program to send/receive data through a serial port from host/slave. This is my current working test code. I created two ports and used a virtual port emulator.
As this is my first paying job, I am wondering if I could have some critical feedback on this.
I have purchased several of your books. I really appreciate your help. Thanks.
I've taken out any code not directly related to the ports.
Imports System.IO.Ports
Class form1
'==set and open port==
'==not using get portname- COM1 to be used as dedicated port as spec==
Private Sub btnReSet_Click(sender As Object, e As EventArgs) Handles btnReSet.Click
If SerialPort1.IsOpen = False Then
'==Open and set COM1 as host==
Try
'==Set COM1 as portname==
SerialPort1.PortName = "COM1"
'==Port settings==
SerialPort1.BaudRate = 9600
SerialPort1.Parity = Parity.None
SerialPort1.StopBits = StopBits.One
SerialPort1.DataBits = 8
SerialPort1.ReadTimeout = 100
'==Open port==
SerialPort1.Open()
rtbCom1.Text = "COM1 Ready"
tmrPoll.Start()
Catch ex As Exception
rtbCom1.Text = "open error " & ex.Message
End Try
End If
'==Used to test data send/rec==
If SerialPort2.IsOpen = False Then
Try
SerialPort2.PortName = "COM2"
SerialPort2.BaudRate = 9600
SerialPort2.Parity = Parity.None
SerialPort2.StopBits = StopBits.One
SerialPort2.DataBits = 8
SerialPort2.Open()
rtbCom2.Text = "COM2 Open"
Catch ex As Exception
rtbCom2.Text = "open error " & ex.Message
End Try
End If
End Sub
'==CONTROL CHARACTERS- as spec==
'==start and stop values==
Dim STX As Byte = &H2
Dim ETX As Byte = &H3
'==Acknowledgment==
Dim ACK As Byte = &H6
'==class and address==
Dim DeviceClass As String = "E"
Dim DeviceAddress As String = "1"
'==Command to read==
Dim DeviceRead As String = "R"
'==Command to Write==
Dim DeviceWrite As String = "W"
'==[[[stx(start), device class, device address, device command, register register (REG), device data(D1 D0), etx(end)]]]==
'==array of register values, i=index==
'==note for self==='hex15='NAK!==
Dim REG = New String() {"22", "23", "2F", "30"}
'==FOR ME!!test data==
Dim D1 = New Integer() {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
Dim D0 = New Integer() {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
'==data to send==
Dim portWrite As String
'==data to write==
Dim portRead As String
Private Sub tmrPoll_Tick(sender As Object, e As EventArgs) Handles tmrPoll.Tick
'==FOR ME!!loop counter for testing==
Dim i As Integer = 0
'==timeout error counter==
Dim j As Integer = 0
'==Prevent unnecessary timeout errors/allow time lag for port to open==
Do While SerialPort1.IsOpen = True And SerialPort2.IsOpen = True
'==Loop through Register==
For Each r In REG
Dim portWrite As String = (STX & DeviceClass & DeviceAddress & ACK & r & i & i & ETX)
Try
'==Loop Host Commands for Register==
SerialPort1.WriteLine(portWrite & vbCr)
'==Time for DataReceived Event Handlers to execute==
lst1.Items.Add(STX & DeviceClass & DeviceAddress & ACK & r & i & i & ETX & vbCr)
Catch ex As Exception
rtbCom1.Text = "Write Error: " & ex.Message
End Try
Try
'==readline to separate data==
portRead = SerialPort2.ReadLine()
'==display data in GUI==
lst2.Items.Add(portRead)
'==Get Register Value==
Dim r1 As String
'==Slave data values==
Dim d As Integer
'==[[[STX & DeviceClass & DeviceAddress & ACK & REG1 & REG0 (REG) & D0 & D1 & ETX]]]==
'==2-E-1-6-r-r-X-X-3==
'==Get the Data Value for Individual Register==
r1 = portRead.Substring(4, 2)
'==convert data to integer, so data can be displayed graphically==
d = CInt(portRead.Substring(6, 2))
'==Display received substring values==
Select Case r1
Case Is = "22"
'list box until advised.
lst1.Items.Add(r1 & d)
Case Is = "23"
'==display data as shape==
shpTemp.Width = d * 2
Case Is = "2F"
shpAmp.Width = d
Case Is = "30"
shpVolt.Width = d * 3
End Select
Catch ex As Exception
lst2.Items.Add("Read error: " & ex.Message)
End Try
If j > 2 Then
rtbCom2.Text = "Operation Aborted: 3 timeout errors."
'==Stop program if 3 timeout errors- as spec/closed port should terminate Do while==
SerialPort1.Close()
rtbCom1.Text = "port closed - Operation Aborted: 3 timeout errors."
' shpAmp.Width = -1
shpTemp.Width = -1
shpVolt.Width = -1
tmrPoll.Stop()
Exit Do
End If
Next
i += 1
If i > 9 Then
i = 0
End If
Loop
End Sub
End Class
