zhidaoshenmo
雖然我們不是“富二代”,但是我們還有成為“富一代”的機(jī)會(huì)。
級(jí)別: 家園?
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本系統(tǒng)以PC對(duì)基于PLC的交通燈控制系統(tǒng)的監(jiān)控為例,在上位機(jī)與PLC正常通信的前提下,設(shè)計(jì)如下界面。窗體的內(nèi)容主要包括,四大區(qū):端口、站號(hào)選擇區(qū),設(shè)定時(shí)間輸入?yún)^(qū),監(jiān)控顯示區(qū),控制按紐區(qū)。從站號(hào)選擇區(qū)選擇不同站號(hào)即不同PLC,實(shí)現(xiàn)對(duì)多個(gè)PLC的實(shí)時(shí)監(jiān)控。 3.1 串口初始化程序 If MSComm1.PortOpen <> True Then MSComm1.PortOpen=True End If MSComm1.Settings=“9600,E,7,2” MSComm1.InputLen=0 MSComm1.InBufferCount=0 MSComm1.InputMode=comInputModeText MSComm1.Handshaking=comNone 3.2 計(jì)算機(jī)與PLC通信的VB程序 Public Function ReadData(ByVal InputStr As String, ByVal Num1 As Integer, ByVal Num2 As Integer) As String Dim OutputStr As String Dim InString As String Dim ReturnStr As String Dim EndString As String Dim FCSString As String Dim ReturnFCSString As String Form1.MSComm1.InBufferCount=0 OutputStr=InputStr+FCS(InputStr)+“*” If Form1.MSComm1.PortOpen=True Then Form1.MSComm1.Output=OutputStr+Chr$(13)’按照PLC幀格式輸出 End If Do DoEvents Loop Until Form1.MSComm1.InBufferCount >=Num2’返回幀的長(zhǎng)度 InString=Form1.MSComm1.Input EndString=Mid$(InString,6,2)’取返回幀的響應(yīng)碼 If EndString <> “00”Then ReadData=“Error” Exit Function End If EndString=Mid$(InString,1,Len(InString)-4) ReturnFCSString=Mid$(InString, Len(InString) -3,2)’取返回幀校驗(yàn)碼 FCSString=FCS(EndString) If FCSString <> ReturnFCSString Then ReadData=“Error” Exit Function End If If Len(InString)>=Num2 Then ReturnStr=Mid$(InString, Len(InString)-Num1-3, Num1)’取返回幀的數(shù)據(jù),其度為Num1 ReadData = ReturnStr End If End Function |
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