PC与三菱PLC的通信程序

3、mlengthAsByteRcvlen=-1'接收数据存放数组的下标初始化length=Len(inString)'求形参传递过来的字符串的长度ReDimoutdata(0Tolength)ReDimoutdata(0Tolength+1)'重新定义发送数据数组，其元素个数为length+1outdata(0)=&H2'命令报文以控制代码STX开始outdata(length+1)=&H3Fori=1Tolength'字符串转换为ASCII码，送入发送数组outdata(i)=Asc(Mid(inString,i,1))NextiCallFC

4、Scheck(outdata)'产生校验和，形成发送帧length=UBound(outdata)'ReDimPreserveoutdata(0Tolength)'重新定义发送数据数组outdata_1=BitConverter.ToString(outdata)frmParam.SerialPort1.Write(outdata,0,outdata.Length)'发送命令帧frmPlc.ListBox1.Items.Add(outdata_1)EndSub'求和校验子程序PrivateSubFCScheck(ByRefoutdata()A

5、sByte)DimBufLenAsInteger,BufAsString'定义字符串长度变量和字符串变量DimiAsInteger'DimCheckSumAsLong'定义校验和变量BufLen=UBound(outdata)'求outdata数组可用最大下标CheckSum=0'初始化校验和Fori=LBound(outdata)+1ToUBound(outdata)'求和时不包括的控制代码CheckSum=(CheckSum+outdata(i)And&HFF)'对outdata数组的元素求和，只保留低位字节Nexti'若校验和只有一位，

6、则高位添零，补足为2Buf=IIf(Len(Hex(CheckSum))=1,"0"&Hex(CheckSum),Hex(CheckSum))ReDimPreserveoutdata(BufLen+2)outdata(BufLen+1)=Asc(Mid(Buf,1,1))'校验和转换为ASCII码，低位在前outdata(BufLen+2)=Asc(Mid(Buf,2,1))EndSubPrivateSubY0_Click(senderAsObject,eAsEventArgs)HandlesY0.ClickStaticDimflagAsBo

7、oleanIfflag=0TheninString="70005"flag+=1ElseinString="80005"flag=0EndIfCallsend(inString)'调用发送子程序EndSubPrivateSubY1_Click(senderAsObject,eAsEventArgs)HandlesY1.ClickStaticDimflagAsBooleanIfflag=0TheninString="70105"flag+=1ElseinString="80105"flag=0EndIfCallsend(inString)'调用

8、发送子程序EndSubPrivateSubY2_Click(senderAsObject,eAsEventArgs)HandlesY2.ClickStaticDim