在VB.Net中使用多个定时器

Question

我想在Visual 2012中使用多个定时器来读取PLC (可编程逻辑控制器，电子产品)中的多个寄存器中的数据。当我只使用一个计时器读取一个寄存器时，我得到了正确的数据，但是当我想读取另一个寄存器时，接收到的数据都没有正确显示(从0到实际值之间波动)。我用我朋友的图书馆来实现这一目标。所以我不知道图书馆..。下面是代码：

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)，那么我就得到了适当的值。但是我想从多个寄存器中显示多个值。

Answer 1

谢谢你的帮助。我想出来了，问题是时间问题。我把计时器间隔从100毫秒提高到200毫秒，一切正常。然后，我添加了第三个plc.ReadWord，程序再次开始不正常运行。然后，我再次把计时器间隔增加到300毫秒，一切都很正常。谢谢。

Answer 2

我怀疑线程问题正在发生。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