Question

我想在Visual Studio 2012中使用多个计时器从PLC（可编程逻辑控制器，电子设备）中的多个寄存器读取数据。当我只使用一个定时器读取一个寄存器时，我得到了正确的数据但是当我想要读取另一个寄存器时，没有一个接收的数据正确显示（它从0到实际值波动）。我用我朋友的图书馆来实现这个目标。所以我不知道图书馆.. 这是代码：

Imports Communication

Public Class Form1
    Dim plc As PLCEthernetReadWrite

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        plc = New PLCEthernetReadWrite("192.168.1.5")
        Timer1.Start()
        Timer2.Start()
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        Label1.Text = plc.ReadWord("404507") 'Where 404507 is register no.
        Label4.Text = Val(Label1.Text) / 100
    End Sub

    Private Sub Timer2_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer2.Tick
        Label1.Text = plc.ReadWord("002071") 'Where 002071 is register no.
        Label4.Text = Val(Label1.Text) / 100
    End Sub
End Class

如果我只使用一个计时器（timer1或timer2），那么我得到适当的值。但我想从多个寄存器中显示多个值。

Answer 1

我怀疑存在线程问题。尽量避免同时调用plc.ReadWord。

    Private plcLock As New Object

    Private Function GetPlcValue(plc As PLCEthernetReadWrite, word As String) As String
        SyncLock plcLock
            Return plc.ReadWord(word)
        End SyncLock
    End Function

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        Label1.Text = GetPlcValue(plc, "404507") 'Where 404507 is register no.
        Label4.Text = Val(Label1.Text) / 100
    End Sub

    Private Sub Timer2_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer2.Tick
        Label1.Text = GetPlcValue(plc, "002071") 'Where 002071 is register no.
        Label4.Text = Val(Label1.Text) / 100
    End Sub

Answer 2

感谢您的帮助。我想通了，问题在于时间问题。我将计时器间隔从100毫秒增加到200毫秒，一切正常。然后我添加了第三个plc.ReadWord，程序又开始行为不端。然后我再次将计时器间隔增加到300毫秒，并且一切都运行良好。感谢。

在VB.Net中使用多个计时器

2 个答案: