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

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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)比較后一位為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(hào)

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 + Hex(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 + Hex(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 + Hex(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(zhǎng)度

av = MSComm1.Input ‘將串口數(shù)據(jù)取出來

For i = 0 To ReDataLen ? 1

FGetData = FGetData & Right(“00″ & Hex(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(zhǎng)度

av = MSComm1.Input ‘將串口數(shù)據(jù)取出來

For i = 0 To ReDataLen ? 1

FGetData = FGetData & Right(“00″ & Hex(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(zhǎng)度

av = MSComm1.Input ‘將串口數(shù)據(jù)取出來

For i = 0 To ReDataLen ? 1

FGetData = FGetData & Right(“00″ & Hex(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

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