三菱FX系列PLC与计算机无协议通讯.docx

02h30h30h,34h03h37h,34hSTX1STDATA2NDDATA.....LASTDATAETXSUM02h33h35h38h34h03h44h,36h31h,30h,46h,36h一、FX系列与计算机通信所用到的命令码:命令命令码目标设备元件读取CMD0X,Y,M,S,T,C,D元件写入CMD1X,Y,M,S,T,C,D强迫ONCMD7X,Y,M,S,T,C强迫OFFCMD8X,Y,M,S,T,C所用字符:ENQ05H来自计算机的请求信号ACK06HPLC正确响应NAK15HPLC错误响应STX02H报文开始ETX03H报文结束二、协议报文分析(举例):始命令首地址位数终和校验STXCMDGROUPADDRESSBYTESETXSUM例子:从D123开始读取4个字节数据地址算法:address=address*2+1000h再转换成ASCII31h,30h,46h,36hPLC返回注:最多可以读取64个字节的数据例子:从指定的存储器单元读到3584这个数据 2、DEVICEWRITE(向PLC软设备写入值)始命令首地址位数数据终和校验STXCMDGROUPADDRESSBYTES1STDATA2NDDATA......LASTDATAETXSUM30h,34h02h31h31h,30h,46h,36h03h34h,39h33h,34h,31h,32h,43h,44h,41h,42h例子:向D123开始的两个存储器中写入1234,ABCDPLC返回ACK(06H)接受正确NAK(15H)接受错误 3、位设备强制置位/复位FORCEON置位始命令地址终和校验STXCMDADDRESSETXSUM02h37haddress03hsumFORCEOFF复位始命令地址终和校验STXCMDADDRESSETXSUM02h38haddress03hsum