协议说明

HostLink C-mode可以直接通过PC连接欧姆龙PLC，可以直接读取/写入欧姆龙PLC寄存器的协议。

        其中分为1对1，以及1对N模式，1对1表示1台PC只能连接一个PLC，1对N表示1台PC可以通过协议连接多个PLC。而1:1与1:N在数据帧上也有所不同，其中1:1不需要带有PLC站号，这点比较好理解，毕竟只有一个PLC就无所谓区别是哪一个PLC了。连接图示如下所示:

命令发送和响应帧描述

        数据帧一般包含:

        1、起始符 '@'    1byte        

        2、站号  BCD格式 0-31的数  2byte

        3、头部 一般为命令的类型 2byte

        4、内容   命令的参数

        5、FCS  校验码  对FCS之前的字节数组进行异或  2byte

        6、结束码  PLC回复时带有，表示是否有异常 

        7、结束符  "*/r" 2byte  注意'/r'是回车符，与'/n'是不同的

 Command Frame Format

Response Frame Format

 C-MODE协议关于分帧的规定

        当发送或接受的数据帧超过131字节时，将会对发送和结束的数据帧进行分割，会分割多个不同的帧来进行发送。最后如果不是最后一帧，每个帧的最后一个字符为'\r'，用于分割不同的帧。结束的帧与正常的帧一样结尾"*\r"。因为1:1和1:N发送的帧有所不同，故在分帧上发送的字数也不尽相同。我们可以知道1:1有可能会多发一个数。

        未发送完成的，即没有Terminator，只有'\r'，那么回应方需要先发一个'\r'才会继续发送下一个帧。直到发送了Terminator或接收到Terminator。

       PC发送数据时产生分帧时的规定，如下图所示:

         PC发送数据时产生分帧时的规定，如下图所示:

 C-MODE可以读写的寄存器

C-MODE读取寄存器时的具体协议

        读取规则除了RG和RE之外，其他的Memory读取协议都是一样的。这两个的读取可查阅官方文档。

 C-MODE寄存器写  -Monitor模式下才能正确写入

        常用的寄存器除了WE之外其他都差不多的帧内容

 C#实现协议

读取寄存器部分代码

        目前不支持RE,RG。方法主体使用泛型来编写，返回值设计了一个泛型类型表示通讯是否成功、通讯时间、以及读取到的寄存器内容。返回的类型设计为:

    public class HostLinkResult<T> where T : unmanaged{public bool IsSuccessful { get; set; }public IList<T> Results { get; set; }public long CommunicationTime { get; set; }}

方法主体，分为发送命令和解析返回帧。返回帧为16进制的多段字，可以先将及写入Ilist<short>中，在全部写入IList<T>中。

        public HostLinkResult<T> Read<T>(int begin, int length, RegisterType readType) where T : unmanaged{Stopwatch sw = new Stopwatch();sw.Restart();HostLinkResult<T> result = new HostLinkResult<T>();var size = Marshal.SizeOf(default(T));string commandStr = "";commandStr += _firstChar;if (_unitNumber >= 0){commandStr += _unitNumber.ToString("X2");}commandStr += $"{GetReadHeaderCode(readType)}";commandStr += $"{begin:0000}";var registerNumber = (size / 16 * length);  if (registerNumber < 1) registerNumber = 1; //寄存器数量必须大于1commandStr += $"{registerNumber:0000}";Tuple<bool, List<short>> r = SendReadCommand(commandStr, readType);result.IsSuccessful = r.Item1;result.CommunicationTime = sw.ElapsedMilliseconds;if (!r.Item1) return result;byte[] bytes = BytesHelper.StructsToBytes(r.Item2);result.Results = BytesHelper.BytesToStructs<T>(bytes);result.CommunicationTime = sw.ElapsedMilliseconds;return result;}

读取寄存器帧的命令，发送字符串的生成方法SendReadCommand如下:

        /// <summary>/// 处理读取命令  /// </summary>/// <param name="commandStr"></param>/// <returns></returns>private Tuple<bool, List<short>> SendReadCommand(string commandStr, RegisterType readType){commandStr += $"{GetChecksum(commandStr)}";commandStr += "*\r";string resultStr = "";List<short> result = new List<short>();
#if DEBUGWriteToLog($"PC=>PLC\t:{commandStr}");
#endif_serialPort.Write(commandStr);try{string curFrame = "";while (true){curFrame = _serialPort.ReadTo("\r");    //接收到一帧    读后就没有\r了
#if DEBUGWriteToLog($"PLC=>PC\t:{curFrame}");
#endifvar checksum = GetChecksum(curFrame.Substring(0, curFrame.Length - 3));var fcs = curFrame.Substring(curFrame.Length - 3, 2);if (checksum != fcs)//检测校验码{_lastErrorMessage = "The received data FCS error";
#if DEBUGWriteToLog($"Error\t:{_lastErrorMessage}");
#endifreturn new Tuple<bool, List<short>>(false, result);}if (curFrame.IndexOf("*") == -1)  //判断是否是结束符  当前不是结束符{
#if DEBUGWriteToLog($"Info\t:Current frame isn't end.");
#endifresultStr += curFrame.Substring(0, curFrame.Length - 3); //去掉FCS和Terminator fcs效验过留着没用了}else{WriteToLog($"Info\t:Current frame is end.");resultStr += curFrame.Substring(0, curFrame.Length - 3);break;  //这里退出}_serialPort.Write("\r");  //发送一个回车}string errCode = "";if (_unitNumber >= 0){errCode = resultStr.Substring(5, 2);if (!CheckErrorCode(errCode)) return new Tuple<bool, List<short>>(false, result);resultStr = resultStr.Remove(0, 7);  //已经验证过ErrCode 可以把头部去掉}else{errCode = resultStr.Substring(3, 2);if (!CheckErrorCode(errCode)) return new Tuple<bool, List<short>>(false, result);resultStr = resultStr.Remove(0, 5);  //已经验证过ErrCode 可以把都去掉}
#if DEBUGWriteToLog($"resultStr is\t:{resultStr}");
#endifif (readType == RegisterType.TC_Status){foreach (var c in resultStr){result.Add(c == '0' ? (short)0 : (short)1);}}else{for (int i = 0; i <= resultStr.Length - 4; i += 4){result.Add(short.Parse(resultStr.Substring(i, 4), System.Globalization.NumberStyles.HexNumber));}}return new Tuple<bool, List<short>>(true, result);}catch (Exception exp)   //一般是超时的异常{_lastErrorMessage = exp.StackTrace;
#if DEBUGWriteToLog($"Error\t:{_lastErrorMessage}");
#endifreturn new Tuple<bool, List<short>>(false, result);}}

C-MODE写入寄存器的具体代码

写入代码返回比较简单，主要是验证是否正确的写入。具体代码如下

      public bool Write<T>(int begin, IList<T> datas, RegisterType writeType) where T : unmanaged{Stopwatch sw = new Stopwatch();sw.Restart();string commandStr = "";commandStr += _firstChar;if (_unitNumber >= 0){commandStr += _unitNumber.ToString("X2");}commandStr += $"{GetWriteHeaderCode(writeType)}";commandStr += $"{begin:0000}";var bytes = BytesHelper.StructsToBytes(datas);var words = BytesHelper.BytesToStructs<short>(bytes);foreach (var word in words){commandStr += $"{word:X4}";}if (!SendWriteCommand(commandStr, writeType)) return false;else return true;}

读取寄存器帧的命令，发送字符串的生成方法SendWriteCommand如下:

   private bool SendWriteCommand(string commandStr, RegisterType writeType){commandStr += GetChecksum(commandStr);  //添加验证码string reply = "";  //欧姆龙回复的字符串string replyCheckSum = "";string errorCode = "";if (commandStr.Length <= 129){commandStr += "*\r";    //所有要发送的数据_serialPort.Write(commandStr);
#if DEBUGWriteToLog($"PC=>PLC\t:{commandStr}");
#endifreply = _serialPort.ReadTo("\r");
#if DEBUGWriteToLog($"PLC=>PC\t:{reply}");
#endifreplyCheckSum = reply.Substring(reply.Length - 3, 2);if (replyCheckSum != GetChecksum(reply.Substring(0, reply.Length - 3))){_lastErrorMessage = "The received data FCS error";
#if DEBUGWriteToLog($"Error\t:{_lastErrorMessage}");
#endifreturn false;}errorCode = "";if (_unitNumber >= 0)errorCode = reply.Substring(5, 2);else errorCode = reply.Substring(3, 2);
#if DEBUGWriteToLog($"Error code\t:{errorCode}\r");
#endifif (!CheckErrorCode(errorCode)) return false;return true;}else{string firstFrame = "";string residueStr = "";if (_unitNumber > 0){firstFrame = commandStr.Substring(0, 127);  //写入头部和前30个字residueStr = commandStr.Remove(0, 127);}else{firstFrame = commandStr.Substring(0, 125);  //写入头部和前30个字residueStr = commandStr.Remove(0, 125);}firstFrame += GetChecksum(firstFrame + "\r");_serialPort.Write(firstFrame);
#if DEBUGWriteToLog($"PC=>PLC\t:{firstFrame}\r");
#endifwhile (true){reply = _serialPort.ReadTo("\r");if (reply.IndexOf("*") != -1)    //已经是结束帧  其他的帧只是回车符{replyCheckSum = reply.Substring(reply.Length - 3, 2);if (replyCheckSum != GetChecksum(reply.Substring(0, reply.Length - 3))){_lastErrorMessage = "The received data FCS error";
#if DEBUGWriteToLog($"Error\t:{_lastErrorMessage}\r");
#endifreturn false;}errorCode = "";if (_unitNumber >= 0)errorCode = reply.Substring(5, 2);else errorCode = reply.Substring(3, 2);
#if DEBUGWriteToLog($"Error code\t:{errorCode}\r");
#endifif (!CheckErrorCode(errorCode)) return false;return true;}else   //不是结束帧  只回复回车。  没有FCS{string sendCurFrame = "";//需要发送的当前帧if (residueStr.Length / 4 <= 31)   //需要发送的最后一帧  31 * 4 = 124{sendCurFrame = residueStr;  //全部发送sendCurFrame += GetChecksum(sendCurFrame);_serialPort.Write(sendCurFrame + "*\r");WriteToLog($"PC=>PLC\t:{sendCurFrame}");}else{sendCurFrame = residueStr.Substring(0, 124);  //发送31字residueStr.Remove(0, 124);sendCurFrame += GetChecksum(sendCurFrame);_serialPort.Write(sendCurFrame + "\r");WriteToLog($"PC=>PLC\t:{sendCurFrame}");}}}}}

NOTE

由于本人没有欧姆龙PLC做验证，只是在朋友的帮助下验证了几个命令。所以C#代码仅供参考。