每隔1秒从PLC收集数据-希望在数据更改时获取数据
每隔1秒从PLC收集数据-希望在数据更改时获取数据
提问于 2018-06-06 18:07:52
我目前正在用easyModbus (使用Visual Basic)每1秒用一个定时器从我的PLC收集数据，然后我想把数据插入到数据库中。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-绿色，2-黄色，3-红色，4-蓝色，我有一个计时器，可以测量从红灯亮起到亮起的经过时间。
我想要将时间数据记录到database....when happened...when中，如果错误得到修复的话。但是随着我的1秒刷新，它每1秒写入我的数据，我需要它只在它changed...and时写入数据，我也不想每一秒都询问PLC，因为我不需要这样做。
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回答 1
Stack Overflow用户
回答已采纳
发布于 2018-06-07 04:10:23
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.]注意，第一个值是写入数据库的，因为prevValue被初始化为r(t)永远不会有的值。在此之后，仅当r(t) <> r(t-1)时才会发生写入数据库。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/50717720
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