一直看到有些朋友在問ModBus主從站的通訊問題，今天抽空兒給大家發(fā)幾篇。
事先申明，我是調(diào)用的主從站庫，庫本身并不是我編寫的，我沒有那么大的能耐。
另外，上位機(jī)是用VB編寫，VB本身不是很熟，如果有什么錯(cuò)誤，請大家海諒。
最后，這僅僅只是一個(gè)測試程序，如果各位想用到商業(yè)方面，還需要各位自己去完善。
說明：PLC從站，PC作主站，用ModBus協(xié)議進(jìn)行通訊。PC機(jī)讀取PLCVW區(qū)的數(shù)據(jù)；PC機(jī)還讀取PLC內(nèi)部I或者O地址的狀態(tài)。
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以下是PLC程序?qū)崿F(xiàn)，方便貼出，已轉(zhuǎn)換為STL
TITLE=程序注釋
Network 1 // 網(wǎng)絡(luò)標(biāo)題
// 在第一個(gè)循環(huán)周期內(nèi)初始化Modbus從站協(xié)議
LD SM0.1
CALL SBR3, 1, 12, 9600, 0, 0, 128, 32, 1000, &VB0, M10.1, MB11
Network 2
// 在每個(gè)循環(huán)周期內(nèi)執(zhí)行Modbus 從站協(xié)議
LD SM0.0
CALL SBR1, M10.2, MB12
Network 3
LD SM0.0
MOVW AIW0, VW100
/I +54, VW100
MOVW AIW2, VW102
/I +54, VW102
MOVW AIW4, VW104
/I +54, VW104
MOVW AIW6, VW106
/I +54, VW106
Network 4
LD SM0.0
= Q0.0
Network 5
LD I0.0
= Q0.1
Network 6
LD I0.1
= Q0.2
///////////////////////////////////
以下是VB源碼
Option Explicit
Private Declare Function GetTickCount Lib "kernel32" () As Long
Dim x1
Dim p11, p12, p13, p14, p15, p16, p17, p18
Function CRC16(data() As Byte) As String
Dim CRC16Lo As Byte, CRC16Hi As Byte 'CRC寄存器
Dim CL As Byte, CH As Byte '多項(xiàng)式碼&HA001
Dim SaveHi As Byte, SaveLo As Byte
Dim i As Integer
Dim Flag As Integer
CRC16Lo = &HFF
CRC16Hi = &HFF
CL = &H1
CH = &HA0
For i = 0 To UBound(data)
CRC16Lo = CRC16Lo Xor data(i) '每一個(gè)數(shù)據(jù)與CRC寄存器進(jìn)行異或
For Flag = 0 To 7
SaveHi = CRC16Hi
SaveLo = CRC16Lo
CRC16Hi = CRC16Hi 2 '高位右移一位
CRC16Lo = CRC16Lo 2 '低位右移一位
If ((SaveHi And &H1) = &H1) Then '如果高位字節(jié)最后一位為1
CRC16Lo = CRC16Lo Or &H80 '則低位字節(jié)右移后前面補(bǔ)1
End If '否則自動(dòng)補(bǔ)0
If ((SaveLo And &H1) = &H1) Then '如果LSB為1，則與多項(xiàng)式碼進(jìn)行異或
CRC16Hi = CRC16Hi Xor CH
CRC16Lo = CRC16Lo Xor CL
End If
Next Flag
Next i
Dim ReturnData(1) As Byte
ReturnData(0) = CRC16Hi 'CRC高位
ReturnData(1) = CRC16Lo 'CRC低位
CRC16 = ReturnData
End Function
Private Sub about_Click()
frmabout.Show
End Sub
Private Sub Form_Load() '初始化
Timer1.Enabled = False '定時(shí)器1無效
Timer1.Interval = 1000 '定時(shí)器1時(shí)間為1S
Timer2.Enabled = True '定時(shí)器2有效
Timer2.Interval = 1000 '定時(shí)器2時(shí)間為1S
Text1.Text = ""
Text2.Text = ""
Text3.Text = ""
Text4.Text = ""
Text5.Text = ""
Text6.Text = ""
Text8.Text = ""
Text10.Text = ""
MSComm1.CommPort = 1 '設(shè)定端口號
MSComm1.Settings = "9600,n,8,1" '設(shè)定通訊波特率
MSComm1.InBufferSize = 1024 '接收緩沖器大小
MSComm1.OutBufferSize = 1024 '輸出緩沖器大小
MSComm1.InputMode = comInputModeBinary '以二進(jìn)制傳輸
MSComm1.RThreshold = 1 '
MSComm1.SThreshold = 0
MSComm1.InputLen = 0 '讀取接收緩沖器所有字符
MSComm1.OutBufferCount = 0 '清空發(fā)送緩沖區(qū)
MSComm1.InBufferCount = 0 '清空接收緩沖區(qū)
If MSComm1.PortOpen = False Then
Command3.Caption = "打開串口"
Else
Command3.Caption = "關(guān)閉串口"
End If
End Sub
Private Sub Command1_Click()
Timer1.Enabled = True
End Sub
Private Sub Command2_Click() '退出程序，定時(shí)器1無效
Timer1.Enabled = False
Cls
Unload Me
End Sub
Private Sub Command3_Click()
On Error Resume Next
If MSComm1.PortOpen = False Then
MSComm1.PortOpen = True
Else
MSComm1.PortOpen = False
End If
If MSComm1.PortOpen Then '打開關(guān)閉按鈕顯示文字
Command3.Caption = "關(guān)閉串口"
Else
Command3.Caption = "打開串口"
End If
If Err Then '打開串口失敗，則顯示出錯(cuò)信息
MsgBox Error$, 48, "錯(cuò)誤信息"
Exit Sub
End If
End Sub
Private Sub Timer1_Timer() '讀V存儲(chǔ)區(qū)數(shù)據(jù)
Dim CRC() As Byte
Dim FGetData As String
Dim aa() As Byte
Dim s As String
Dim str As String
Dim i As Integer
Dim bb, cc As String
ReDim aa(5) As Byte '定義動(dòng)態(tài)數(shù)組
aa(0) = &HC
aa(1) = &H3
aa(2) = &H0
aa(3) = &H32
aa(4) = &H0
aa(5) = &H4
CRC = CRC16(aa)
str = CRC
s = ""
For i = 1 To LenB(str)
s = s + he(AscB(MidB(str, i, 1)))
Next i
bb = Right(s, 2)
cc = Mid(s, 1, 2)
If Len(s) < 4 Then
cc = Mid(s, 1, 1)
End If
ReDim Preserve aa(0 To 7) As Byte
aa(6) = Val("&H" & bb)
aa(7) = Val("&H" & cc)
MSComm1.OutBufferCount = 0 '清空輸出寄存器
MSComm1.Output = aa
FGetData = ReceiveData
Text5.Text = FGetData
p11 = Val("&H" & Mid(FGetData, 7, 4))
p12 = Val("&H" & Mid(FGetData, 11, 4))
p13 = Val("&H" & Mid(FGetData, 15, 4))
p14 = Val("&H" & Mid(FGetData, 19, 4))
End Sub
Private Sub Command4_Click() 'I狀態(tài)
Dim CRC() As Byte
Dim FGetData As String
Dim aa() As Byte
Dim s As String
Dim str As String
Dim i As Integer
Dim bb, cc As String
ReDim aa(5) As Byte '定義動(dòng)態(tài)數(shù)組
aa(0) = &HC
aa(1) = &H2
aa(2) = &H0
aa(3) = &H0
aa(4) = &H0
aa(5) = &H1
CRC = CRC16(aa)
str = CRC
s = ""
For i = 1 To LenB(str)
s = s + he(AscB(MidB(str, i, 1)))
Next i
bb = Right(s, 2)
cc = Mid(s, 1, 2)
If Len(s) < 4 Then
cc = Mid(s, 1, 1)
End If
ReDim Preserve aa(0 To 7) As Byte
aa(6) = Val("&H" & bb)
aa(7) = Val("&H" & cc)
MSComm1.OutBufferCount = 0 '清空輸出寄存器
MSComm1.Output = aa
FGetData = IReceiveData
p17 = Val("&H" & Mid(FGetData, 7, 2))
p18 = Val("&H" & Mid(FGetData, 9, 2))
End Sub
Private Sub Command5_Click() 'Q狀態(tài)
Dim CRC() As Byte
Dim FGetData As String
Dim aa() As Byte
Dim s As String
Dim str As String
Dim i As Integer
Dim bb, cc As String
ReDim aa(5) As Byte '定義動(dòng)態(tài)數(shù)組
aa(0) = &HC
aa(1) = &H1
aa(2) = &H0
aa(3) = &H0
aa(4) = &H0
aa(5) = &H1
CRC = CRC16(aa)
str = CRC
s = ""
For i = 1 To LenB(str)
s = s + he(AscB(MidB(str, i, 1)))
Next i
bb = Right(s, 2)
cc = Mid(s, 1, 2)
If Len(s) < 4 Then
cc = Mid(s, 1, 1)
End If
ReDim Preserve aa(0 To 7) As Byte
aa(6) = Val("&H" & bb)
aa(7) = Val("&H" & cc)
MSComm1.OutBufferCount = 0 '清空輸出寄存器
MSComm1.Output = aa
FGetData = QReceiveData
p15 = Val("&H" & Mid(FGetData, 7, 2))
p16 = Val("&H" & Mid(FGetData, 9, 2))
End Sub
Private Function ReceiveData() As String '返回V存儲(chǔ)器區(qū)數(shù)據(jù)
Dim FGetData As String
Dim t1 As Long
Dim av As Variant
Dim i As Integer
Dim ReDataLen As Integer
FGetData = ""
t1 = GetTickCount() '取時(shí)間，做延時(shí)用
Do '循環(huán)等待接收數(shù)據(jù)
DoEvents
If MSComm1.InBufferCount > 0 Then '串口有數(shù)據(jù)了
ReDataLen = MSComm1.InBufferCount '取數(shù)據(jù)長度
av = MSComm1.Input '將串口數(shù)據(jù)取出來
For i = 0 To ReDataLen - 1
FGetData = FGetData & Right("00" & he(av(i)), 2)
Next i
End If
If Len(FGetData) >= 6 Then
If Len(FGetData) > Val("&H" & Mid(FGetData, 5, 2)) * 2 + 8 Then
ReceiveData = FGetData
Exit Function
End If
End If
If GetTickCount - t1 > 2000 Then '2秒沒收完就不收了
ReceiveData = ""
Exit Function
End If
Loop
End Function
Private Function IReceiveData() As String '反回I狀態(tài)
Dim FGetData As String
Dim t1 As Long
Dim av As Variant
Dim i As Integer
Dim ReDataLen As Integer
FGetData = ""
t1 = GetTickCount() '取時(shí)間，做延時(shí)用
Do '循環(huán)等待接收數(shù)據(jù)
DoEvents
If MSComm1.InBufferCount > 0 Then '串口有數(shù)據(jù)了
ReDataLen = MSComm1.InBufferCount '取數(shù)據(jù)長度
av = MSComm1.Input '將串口數(shù)據(jù)取出來
For i = 0 To ReDataLen - 1
FGetData = FGetData & Right("00" & he(av(i)), 2)
Next i
End If
If Len(FGetData) >= 6 Then
If Len(FGetData) > Val("&H" & Mid(FGetData, 5, 2)) * 2 + 8 Then
IReceiveData = FGetData
Exit Function
End If
End If
If GetTickCount - t1 > 2000 Then '2秒沒收完就不收了
IReceiveData = ""
Exit Function
End If
Loop
End Function
Private Function QReceiveData() As String '反回Q狀態(tài)
Dim FGetData As String
Dim t1 As Long
Dim av As Variant
Dim i As Integer
Dim ReDataLen As Integer
FGetData = ""
t1 = GetTickCount() '取時(shí)間，做延時(shí)用
Do '循環(huán)等待接收數(shù)據(jù)
DoEvents
If MSComm1.InBufferCount > 0 Then '串口有數(shù)據(jù)了
ReDataLen = MSComm1.InBufferCount '取數(shù)據(jù)長度
av = MSComm1.Input '將串口數(shù)據(jù)取出來
For i = 0 To ReDataLen - 1
FGetData = FGetData & Right("00" & he(av(i)), 2)
Next i
End If
If Len(FGetData) >= 6 Then
If Len(FGetData) > Val("&H" & Mid(FGetData, 5, 2)) * 2 + 8 Then
QReceiveData = FGetData
Exit Function
End If
End If
If GetTickCount - t1 > 2000 Then '2秒沒收完就不收了
QReceiveData = ""
Exit Function
End If
Loop
End Function
Private Sub Timer2_Timer()
x1 = x1 + 1
Text10.Text = str(x1)
Text1.Text = str(p11)
Text2.Text = str(p12)
Text3.Text = str(p13)
Text4.Text = str(p14)
Text7.Text = str(p15)
If Text7.Text = 1 Then Text7.BackColor = RGB(255, 0, 255)
If Text7.Text = 0 Then Text7.BackColor = RGB(0, 255, 255)
'Text6.Text = str(p16)
Text9.Text = str(p17)
If Text9.Text = 1 Then Text9.BackColor = RGB(255, 0, 255)
If Text9.Text = 0 Then Text9.BackColor = RGB(0, 255, 255)
'Text8.Text = str(p18)
End Sub
