C# SerialPort 讀寫三菱FX系列PLC
1：串列埠初始化
com = new SerialPort("COM3", 9600, Parity.Even, 7, StopBits.One);
2：開啟關閉串列埠
if (com.IsOpen)
{com.Close();}
com.Open();
if (com.IsOpen)
{ com.Close();}
3：C# ASCII轉字元及字元轉ASCII
public static string Chr(int asciiCode)
{
if (asciiCode >= 0 && asciiCode <= 255)
{
System.Text.ASCIIEncoding asciiEncoding = new System.Text.ASCIIEncoding();
byte[] byteArray = new byte[] { (byte)asciiCode };
string strCharacter = asciiEncoding.GetString(byteArray);
return (strCharacter);
}
else
{
throw new Exception("ASCII Code is not valid.");
}
}
public static int Asc(string character)
{
if (character.Length == 1)
{
System.Text.ASCIIEncoding asciiEncoding = new System.Text.ASCIIEncoding();
int intAsciiCode = (int)asciiEncoding.GetBytes(character)[0];
return (intAsciiCode);
}
else
{
throw new Exception("Character is not valid.");
}
}
4：寫入串列埠的命令字串的和校驗
/// <summary>
/// 和校驗
/// </summary>
/// <param name="data"></param>
/// <returns></returns>
public string SumCheck(string data)
{
int sum = 0;
for (int i = 0; i < data.Length; i++)
{
sum += Asc(data.Substring(i, 1));
}
string res = sum.ToString("X");
res = res.Substring(res.Length - 2, 2);
return res;
}
5：寫入PLC
private void btnWrite_Click(object sender, EventArgs e)
{
string[] write = new string[] { "2","2"}; //將準備寫入PLC的值
//將要寫入的值轉換成16進位制數,補齊兩個位元組,注意高低位元組需要交換
string sWriteData = "";
for (int i = 0; i < write.Length; i++)
{
int val = Convert.ToInt32(write[i].Length>0?write[i]:"0");
string s = val.ToString("X");
while (s.Length<4)
{
s = "0" + s;
}
sWriteData += s.Substring(2,2)+s.Substring(0,2);
}
MessageBox.Show(sWriteData);
//寫入命令,1表示寫入,1194表示D202這個地址的16進位制,04表示D202,D203為4個BYTE,1194=(202*2)+4096的16進位制數,至於用它表示D202的起始位置,三菱故意要這麼麻煩了.
sWriteData = "1119404" + sWriteData + Chr(3);
//chr(2)和chr(3)是構成命令的標誌字元,然後加上校驗和,命令組織完成
sWriteData = Chr(2) + sWriteData + SumCheck(sWriteData);
MessageBox.Show(sWriteData);
//寫入串列埠
com.Write(sWriteData);
//byte[] data = Encoding.ASCII.GetBytes(sWriteData);
//com.Write(data,0,data.Length);
}
6:讀PLC
private void btnRead_Click(object sender, EventArgs e)
{
this.txtRead0.Clear();
string sReadData = "";
//在讀PLC中的資料之前,需要先發個指令給它,讓它將資料傳送到串列埠,下面的字串中,chr(2),chr(3)為PLC命令的格式標誌,0119404中,0表示讀,1194表示D202的起始地址,04表示讀D202,D203兩個字,共4個位元組,66為0119404和chr(3)的校驗和,向串列埠寫入"讀"命令,其實和向plc地址中寫入資料是一樣的,只是沒有資料,用0表示讀
string sReadCmd = Chr(2) + "0119404" + Chr(3) + "66";
com.Write(sReadCmd);
//等待1秒鐘
System.Threading.Thread.Sleep(1000);
// 從串列埠讀資料
byte[] data = new byte[1024];
com.Read(data, 0, 1024);
//如果首位為2,則表示資料有效.這裡有個問題,在第二次讀,第2位才為'2',第三次又是首位為2,需要再測試
if (data[0]==2)
{
string sReceiveData = System.Text.Encoding.ASCII.GetString(data);
//MessageBox.Show(sReceiveData);
//解析命令,將讀到的字元解析成數字,注意高低位的轉換
for (int i = 1; i < 8; i += 4)
{
string sLow = sReceiveData.Substring(i,2);
string sHigh = sReceiveData.Substring(i + 2, 2);
//int res = Convert.ToInt32(sHigh)+ Convert.ToInt32(sLow);
int res = Convert.ToInt32(sHigh,16) + Convert.ToInt32(sLow,16);
this.txtRead0.Text += res.ToString() + ",";
}
}