1、三菱FX系列PLC编程口通信协议举例1、DEVICE READ(读出软设备状态值)计算机向PLC发送:始命令首地址位数终和校验STXCMDGROUP ADDRESSBYTESETXSUM例子:从D123开始读取4个字节数据02h30h31h,30h,46h,36h30h,34h03h37h,34h地址算法:address=address*2+1000h再转换成ASCII31h,30h,46h,36hPLC返回STX1ST DATA2ND DATA.LAST DATAETXSUM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02h33h35h38h34h03h44h
2、,36h2、DEVICE WRITE(向PLC软设备写入值)始命令首地址位数数据终和校验STXCMDGROUP ADDRESSBYTES1ST DATA2ND DATA.LAST DATAETXSUM例子:向D123开始的两个存储器中写入1234,ABCD02h31h31h,30h,46h,36h30h,34h33h,34h,31h,32h,43h,44h,41h,42h03h34h,39hPLC返回ACK (06H) 接受正确NAK (15H) 接受错误3、位设备强制置位/复位FORCE ON置位始命令地址终和校验STXCMDADDRESSETXSUM02h37haddress03hsumF
3、ORCE OFF复位始命令地址终和校验STXCMDADDRESSETXSUM02h38haddress03hsumPLC返回ACK(06H) 接受正确NAK(15H) 接受错误设备强制中的地址公式:Address=Address/8+100h说明:1.帧中的BYTES表示需要读取或者写入的字节数。2.地址算法上有说明。3.累加和是从STX后面一个字节开始累加到ETX的和。三菱FX系列PLC编程口通信协议总览该协议实际上适用于PLC编程端口以及 FX-232AW 模块的通信。感谢网友visualboy提供。通讯格式:命令命令码目标设备DEVICE READ CMD0X,Y,M,S,T,C,DDE
4、VICE WRITE CMD1 X,Y,M,S,T,C,DFORCE ON CMD 7X,Y,M,S,T,CFORCE OFF CMD 8 X,Y,M,S,T,C传输格式: RS232C波特率: 9600bps奇偶: even校验: 累加方式(和校验)字符: ASCII16进制代码: ENQ05H请求ACK06HPLC正确响应NAK15HPLC错误响应STX02H报文开始ETX03H报文结束帧格式:STXCMDDATA.DATAETXSUM(upper)SUM(lower)例子:STX ,CMD ,ADDRESS, BYTES, ETX, SUM02H, 30H, 31H,30H,46H,36H, 30H,34H, 03H, 37H,34HSUM=CMD+.+ETX;30h+31h+30h+46h+36h+30h+34h+03h=74h;累加和超过两位取低两位