用VB做的程序
Sub OnLButtonDown(ByVal Item, ByVal Flags, ByVal x, ByVal y)
Dim objTag1
Dim objTag2
Set objTag1 = HMIRuntime.Tags("1#SCXMX15_0")
objTag1.Read
objTag1.Value = 1
objTag1.Write
Set objTag2 = HMIRuntime.Tags("1#SCXMX20_6")
objTag2.Read
objTag2.Value = 1
objTag2.Write
End Sub这是前进按钮

Sub OnLButtonUp(ByVal Item, ByVal Flags, ByVal x, ByVal y)
Dim objTag1
Dim objTag2
Dim objTag3
Dim objTag4

Set objTag1 = HMIRuntime.Tags("1#SCXMX15_0")
objTag1.Read
objTag1.Value = 0
objTag1.Write
Set objTag2 = HMIRuntime.Tags("1#SCXMX20_6")
objTag2.Read
objTag2.Value = 0
objTag2.Write
Set objTag1 = HMIRuntime.Tags("1#SCXMX15_2")
objTag1.Read
objTag1.Value = 1
objTag1.Write
Set objTag2 = HMIRuntime.Tags("1#SCXMX20_7")
objTag2.Read
objTag2.Value = 1
objTag2.Write
End Sub这是后退按钮,,
请教高手该设计怎样理解?