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了解了它，會使你對串口通信有一個清晰的認識！
通用消息幀
ASCII消息幀 (在消息中的每個8Bit 字節(jié)都作為兩個ASCII字符發(fā)送) 十六進制，ASCII字符0...9，A...F 消息中的每個ASCII字符都是一個十六進制字符組成 每個字節(jié)的位 1個起始位 n個數(shù)據(jù)位，最小的有效位先發(fā)送 1個奇偶校驗位，無校驗則無 1個停止位（有校驗時），2個Bit（無校驗時） 錯誤檢測域 LRC(縱向冗長檢測)
RTU消息幀 8位二進制，十六進制數(shù)0...9，A...F 消息中的每個8位域都是一個兩個十六進制字符組成 每個字節(jié)的位 1個起始位 8個數(shù)據(jù)位，最小的有效位先發(fā)送 1個奇偶校驗位，無校驗則無 1個停止位（有校驗時），2個Bit（無校驗時） 錯誤檢測域 CRC(循環(huán)冗長檢測)
CRC校驗 (http://baike.baidu.com/view/1664507.htm)  public static string CRCCheck(string val) { val = val.TrimEnd(' '); string[] spva = val.Split(' '); byte[] bufData = new byte[spva.Length + 2]; bufData = ToBytesCRC(val); ushort CRC = 0xffff; ushort POLYNOMIAL = 0xa001; for (int i = 0; i < bufData.Length - 2; i++) { CRC ^= bufData[i]; for (int j = 0; j < 8; j++) { if ((CRC & 0x0001) != 0) { CRC >>= 1; CRC ^= POLYNOMIAL; } else { CRC >>= 1; } } } return Maticsoft.DBUtility.HLConvert.ToHex(System.BitConverter.GetBytes(CRC)); } /// <summary> /// 例如把如下字符串轉(zhuǎn)換成字節(jié)數(shù)組 /// AA AA AA AA 0A 00 68 00 06 03 04 54 21 28 22 E5 F3 16 BB BB BB BB 轉(zhuǎn)換為字節(jié)數(shù)組 /// </summary> /// <param name="hex">十六進制字符串</param> /// <returns></returns> public static byte[] ToBytesCRC(string hex) { string[] temp = hex.Split(' '); byte[] b = new byte[temp.Length + 2]; for (int i = 0; i < temp.Length; i++) { b[i] = Convert.ToByte(temp[i], 16); } return b; } /// <summary> /// 將字節(jié)數(shù)據(jù)轉(zhuǎn)換為十六進制字符串，中間用 “ ”分割 如：AA AA AA AA 0A 00 68 00 06 03 04 54 21 28 22 E5 F3 16 BB BB BB BB /// </summary> /// <param name="vars">要轉(zhuǎn)換的字節(jié)數(shù)組</param> /// <returns></returns> public static String ToHex(byte[] vars) { return BitConverter.ToString(vars).Replace('-', ' ').Trim(); } CS校驗(累加和) public static string CSCheck(string str) { if (str.Length == 0) return ""; else str = str.Trim(); byte[] sss = ToBytes(str); int n = 0; for (int i = 0; i < sss.Length; i++) { n += sss[i]; } return ToHex(n); } /// <summary> /// AB CD 12 3B 轉(zhuǎn)換為字節(jié)數(shù)組 /// </summary> /// <param name="hex">十六進制字符串</param> /// <returns></returns> public static byte[] ToBytes(string hex) { string[] temp = hex.Split(' '); byte[] b = new byte[temp.Length]; for (int i = 0; i < temp.Length; i++) { if (temp[i].Length > 0) b[i] = Convert.ToByte(temp[i], 16); } return b; } /// <summary> /// 轉(zhuǎn)換為符合本程序的十六進制格式 /// </summary> /// <param name="var">1 2 3 等。</param> /// <returns>返回十六進制字符串，如果是1-9的話，前面帶零</returns> /// <example>例如: 5 ="05" 12 ="0C" 無論何時，都是兩位數(shù)。 </example> public static string ToHex(int var) { int cs = var; string tmp = ""; if (cs == 0) { tmp = "00"; } while (cs > 0) { int ys; cs = Math.DivRem(cs, 256, out ys); tmp = tmp.Insert(0, string.Format(" {0}", Right("00" + Convert.ToString(ys, 16), 2).ToUpper())); } return tmp.Trim(); } public static string Right(string str, int Length) { if ((Length <= 0) || (str == null)) { return ""; } int length = str.Length; if (Length >= length) { return str; } return str.Substring(length - Length, Length); } LRC校驗(LRC錯誤校驗用于ASCII模式)  /// <summary> /// 取模FF(255) /// 取反+1 /// </summary> /// <param name="writeUncheck"></param> /// <returns></returns> public static string LRCheck(string writeUncheck) { char[] hexArray = new char[writeUncheck.Length]; hexArray = writeUncheck.ToCharArray(); int decNum = 0, decNumMSB = 0, decNumLSB = 0; int decByte, decByteTotal = 0; bool msb = true; for (int t = 0; t <= hexArray.GetUpperBound(0); t++) { if ((hexArray[t] >= 48) && (hexArray[t] <= 57)) decNum = (hexArray[t] - 48); else if ((hexArray[t] >= 65) & (hexArray[t] <= 70)) decNum = 10 + (hexArray[t] - 65); if (msb) { decNumMSB = decNum * 16; msb = false; } else { decNumLSB = decNum; msb = true; } if (msb) { decByte = decNumMSB + decNumLSB; decByteTotal += decByte; } } decByteTotal = (255 - decByteTotal) + 1; decByteTotal = decByteTotal & 255; int a, b = 0; string hexByte = "", hexTotal = ""; double i; for (i = 0; decByteTotal > 0; i++) { b = Convert.ToInt32(System.Math.Pow(16.0, i)); a = decByteTotal % 16; decByteTotal /= 16; if (a <= 9) hexByte = a.ToString(); else { switch (a) { case 10: hexByte = "A"; break; case 11: hexByte = "B"; break; case 12: hexByte = "C"; break; case 13: hexByte = "D"; break; case 14: hexByte = "E"; break; case 15: hexByte = "F"; break; } } hexTotal = String.Concat(hexByte, hexTotal); } return hexTotal; } public void LRCheck(byte[] code) { int sum = 0; foreach (byte b in code) { sum += b; } sum = sum % 255;//取模FF(255) sum = ~sum + 1;//取反+1 string lrc = Convert.ToString(sum, 16); return lrc; }
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