mysql - 每1秒从PLC收集数据-希望在数据变化时获取数据

Question

我目前正在使用 easyModbus(使用 Visual Basic)每 1 秒使用计时器从 PLC 收集数据，稍后我想将数据插入数据库。我的目标是仅当 PLC 内部的值发生变化时才刷新程序中的数据。

例如:我有 4 个 LED，1-绿 2-黄 3-红 4-蓝，并且我有一个计时器，用于测量从红灯亮起到红灯熄灭所耗时。

我想将时间数据记录到数据库中......当错误发生时......当错误修复时。但是，通过我的 1 秒刷新，它每 1 秒写入一次数据，我需要它仅在数据更改时写入数据......而且我也不想每秒询问 PLC，因为我不需要.

Public Sub Refresh_btn_Click() Handles Refresh_btn.Click
    Dim ComError = 0 'Set comm error flag to 0

    Dim Ipaddress As String
    Ipaddress = "127.0.0.1"

    Dim Portaddress As String
    Portaddress = "502"


    Dim ModbusClient As EasyModbus.ModbusClient = New EasyModbus.ModbusClient(Ipaddress, Portaddress) 'Ip address and port Text box = Ip on form

    Try
        ModbusClient.Connect() 'Connect to PLC
    Catch ex As Exception   'What to do when error occurs
        Status_lbl.BackColor = Color.Red
        Status_lbl.ForeColor = Color.White
        Status_lbl.Text = "Error!"
        ComError = 1 'Set comm error flag to 1
    End Try
    If ComError = 0 Then
        Status_lbl.BackColor = Color.Green
        Status_lbl.ForeColor = Color.White
        Status_lbl.Text = "No Error!"

        'First line Andon
        Dim Registers As Integer()
        Registers = ModbusClient.ReadHoldingRegisters(0, 10)
        'Indexing Registers starting with null

        If Registers(0) = 0 Then
            GreenSIGN.BackColor = Color.LightGray
            YellowSIGN.BackColor = Color.LightGray
            RedSIGN.BackColor = Color.LightGray
            BlueSIGN.BackColor = Color.LightGray
        End If

        If Registers(0) = 1 Then
            GreenSIGN.BackColor = Color.Green
        Else
            GreenSIGN.BackColor = Color.LightGray
        End If

        If Registers(0) = 2 Then
            YellowSIGN.BackColor = Color.Yellow
        Else
            YellowSIGN.BackColor = Color.LightGray
        End If

        If Registers(0) = 3 Then
            RedSIGN.BackColor = Color.Red
        Else
            RedSIGN.BackColor = Color.LightGray
        End If

        If Registers(0) = 4 Then
            BlueSIGN.BackColor = Color.Blue
        Else
            BlueSIGN.BackColor = Color.LightGray
        End If
    End If

    ModbusClient.Disconnect()
    'Timer for downtime Static Start-Stop
    Static start_time As DateTime = Now
    Static stop_time As DateTime = Now
    Static start_time2 As DateTime = Now
    Static stop_time2 As DateTime = Now
    Dim elapsed_time As TimeSpan

    'Only Red Andon
    'If for Red andon For Line XXX
    If RedSIGN.BackColor = Color.Red Then
        stop_time = Now
        elapsed_time = stop_time.Subtract(start_time)
        lbl_elapsed_red.Text = elapsed_time.ToString("hh\:mm\:ss")
    Else
        lbl_elapsed_red.Text = "Ok"
        start_time = Now
    End If


    'Only Blue Andon
    'If for Blue andon For Line XXX
    If BlueSIGN.BackColor = Color.Blue Then
        stop_time2 = Now
        elapsed_time = stop_time2.Subtract(start_time2)
        lbl_elapsed_blue.Text = elapsed_time.ToString("hh\:mm\:ss")


    Else
        lbl_elapsed_blue.Text = "Ok"
        start_time2 = Now


    End If

    'Connectin MySQL

    'Try
    '    Dim SQL As String 'SQL Command String
    '    Dim objCmd As New MySqlCommand 'Command
    '    'Connection String to the SQL Database
    '    Dim Con = New MySqlConnection("server=127.0.0.1;user id=root;database=andon")
    '    'SQL Statement - All values must be set for the table
    '    SQL = "INSERT INTO test_andon VALUES ('" & Now.ToString("yyyy/MM/dd") & "', '" & Now.ToString("HH:mm:ss") & "','" & "@dummy" & "', '" & Now.ToString("start_time2") & "', '" & "@dummy" & "', '" & "@dummy" & "')"
    '    Con.Open() 'Open the database connection
    '    objCmd = New MySqlCommand(SQL, Con) 'Set the command
    '    objCmd.ExecuteNonQuery() 'Execute the SQL command
    '    Con.Close() 'Close the database connection
    'Catch ex As Exception 'What to do when an error occurs
    '    Status_lbl.BackColor = Color.Red
    '    Status_lbl.ForeColor = Color.White
    '    Status_lbl.Text = "Database Error Blue vége!"
    'End Try


End Sub




'Timer reping
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
    Timer1.Interval = 100
    Timer1.Enabled = True
    Call Sub() Refresh_btn_Click()
End Sub

Answer 1

您可以存储红灯的状态并检查新值是否与旧值不同。如果是，则写入数据库并更新旧值，否则不执行任何操作。

例如，假设与红灯相关的传入值为r(t):

Imports System.Timers

Module Module1

    Dim t As Integer = 0
    Dim r() As Integer = {0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1}
    Dim prevValue As Integer = Integer.MinValue

    Sub tock(sender As Object, e As ElapsedEventArgs)
        Dim val = r(t)

        Console.Write(val.ToString() & " ")

        If val <> prevValue Then
            Console.WriteLine("Write to database.")
            prevValue = val
        Else
            Console.WriteLine("Do nothing.")
        End If

        t = (t + 1) Mod r.Length

    End Sub

    Sub Main()
        Dim tim As New Timers.Timer With {.Interval = 1000, .AutoReset = True}
        AddHandler tim.Elapsed, AddressOf tock
        tim.Start()

        Console.WriteLine("Tocking... press enter to quit.")

        Console.ReadLine()
        tim.Stop()
        tim.Dispose()

    End Sub

End Module

输出:

Tocking... press enter to quit.
0 Write to database.
1 Write to database.
1 Do nothing.
1 Do nothing.
1 Do nothing.
0 Write to database.
0 Do nothing.
0 Do nothing.
0 Do nothing.
0 Do nothing.
1 Write to database.
0 Write to database.
1 Write to database.
1 Do nothing.
[Carries on until enter is pressed.]

请注意，第一个值会写入数据库，因为 prevValue 已初始化为 r(t) 永远不会有的值。之后，仅当 r(t) <> r(t-1) 时才会写入数据库。