关于串口通讯的问题：
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很明显，你还不知道（不会、不习惯）使用事件驱动的方式接收数据。
建议你仔细看看串口组件（无论VB6还是VB点虐 ）的OnComm事件，你的问题很容易解决。
关于以太网通讯：
在TCP通讯中端口确实可以重用，你百度一下“TCP端口重用”能查到很多示例。
但绝大多数情况下不推荐端口重用，而应该采取服务器端建立连接池的方法。
或者，干脆不用TCP，用UDP解决也可以。
不知道你是不是用51单片机往串口发数据，是的话那是因为51的SBUF最多存放8个字节，所以你发12个字节会分成两次发完。还有在接收的时候最好定义好通信协议，比如加一个侦头，一个侦尾，通过这两个字节的内容来接收数据。
老兄，提问还是给点悬赏分嘛，不要吝啬哪点分，知识是无价的，你给得越多，回答你的人才会越多。
public string hz2py(string hz) //获得汉字的区位码
{
byte[] sarr = System.Text.Encoding.Default.GetBytes(hz);
int len = sarr.Length;
if (len1)
{
byte[] array = new byte[2];
array = System.Text.Encoding.Default.GetBytes(hz);
int i1 = (short)(array[0] - '\0');
int i2 = (short)(array[1] - '\0');
//unicode解码方式下的汉字码
// array = System.Text.Encoding.Unicode.GetBytes(hz);
// int i1 = (short)(array[0] - '\0');
// int i2 = (short)(array[1] - '\0');
// int t1 = Convert.ToInt32(i1,16);
// int t2 = Convert.ToInt32(i2,16);
int tmp=i1*256+i2;
string getpychar="*";//找不到拼音码的用*补位
if(tmp=45217tmp=45252){getpychar= "A";}
else if(tmp=45253tmp=45760){getpychar= "B";}
else if(tmp=47761tmp=46317){getpychar= "C";}
else if(tmp=46318tmp=46825){getpychar= "D";}
else if(tmp=46826tmp=47009){getpychar= "E";}
else if(tmp=47010tmp=47296){getpychar= "F";}
else if(tmp=47297tmp=47613){getpychar= "G";}
else if(tmp=47614tmp=48118){getpychar= "H";}
else if(tmp=48119tmp=49061){getpychar= "J";}
else if(tmp=49062tmp=49323){getpychar= "K";}
else if(tmp=49324tmp=49895){getpychar= "L";}
else if(tmp=49896tmp=50370){getpychar= "M";}
else if(tmp=50371tmp=50613){getpychar= "N";}
else if(tmp=50614tmp=50621){getpychar= "O";}
else if(tmp=50622tmp=50905){getpychar= "P";}
else if(tmp=50906tmp=51386){getpychar= "Q";}
else if(tmp=51387tmp=51445){getpychar= "R";}
else if(tmp=51446tmp=52217){getpychar= "S";}
else if(tmp=52218tmp=52697){getpychar= "T";}
else if(tmp=52698tmp=52979){getpychar= "W";}
else if(tmp=52980tmp=53640){getpychar= "X";}
else if(tmp=53689tmp=54480){getpychar= "Y";}
else if(tmp=54481tmp=55289){getpychar= "Z";}
return getpychar;
}
else
{
return hz;
}
}
public string transpy(string strhz) //把汉字字符串转换成拼音码
{
string strtemp="";
int strlen=strhz.Length;
for (int i=0;i=strlen-1;i++)
{
strtemp+=hz2py(strhz.Substring(i,1));
}
return strtemp;
}
create table tabpy(id int identity,b_begin varbinary(2),b_end varbinary(2),word varchar(2))
insert tabpy select 0xB0A1, 0xB0C4,'A'
union all select 0xB0C5, 0xB2C0,'B'
union all select 0xB2C1, 0xB4ED,'C'
union all select 0xB4EE, 0xB6E9,'D'
union all select 0xB6EA, 0xB7A1,'E'
union all select 0xB7A2, 0xB8C0,'F'
union all select 0xB8C1, 0xB9FD,'G'
union all select 0xB9FE, 0xBBF6,'H'
union all select 0xBBF7, 0xBFA5,'J'
union all select 0xBFA6, 0xC0AB,'K'
union all select 0xC0AC, 0xC2E7,'L'
union all select 0xC2E8, 0xC4C2,'M'
union all select 0xC4C3, 0xC5B5,'N'
union all select 0xC5B6, 0xC5BD,'O'
union all select 0xC5BE, 0xC6D9,'P'
union all select 0xC6DA, 0xC8BA,'Q'
union all select 0xC8BB, 0xC8F5,'R'
union all select 0xC8F6, 0xCBF9,'S'
union all select 0xCBFA, 0xCDD9,'T'
union all select 0xCDDA, 0xCEF3,'W'
union all select 0xCEF4, 0xD1B8,'X'
union all select 0xD1B9, 0xD4D0,'Y'
union all select 0xD4D1, 0xD7F9,'Z'
函数：
create function getfirstpy(@a varchar(200))
returns varchar(100)
as
begin
declare @i int,@j int,@result varchar(100)
set @result=''
set @i=len(@a)
set @j=1
while @j=@i
begin
select @result=@result+word from tabpy where cast(substring(@a,@j,1) as varbinary(2)) between b_begin and b_end
set @j=@j+1
end
return @result
end
GB2312是GBK编码的子集，使用GBK编码函数即可
'GBK编码(结果以百分号%进行分隔)
Public Function GBKEncode(ByVal sInput As String) As String
Dim ret_GBKEncode As String = ""
Dim i As Integer
Dim startIndex As Integer = 0
Dim endIndex As Integer
Dim x() As Byte = System.Text.Encoding.Default.GetBytes(sInput) '字符以及字符串在vb2008中都是以unicode编码存储的
endIndex = x.Length - 1
For i = startIndex To endIndex
ret_GBKEncode = "%" Hex(x(i))
Next
Return ret_GBKEncode
End Function
'GBK解码
Public Function GBKDecode(ByVal sInput As String) As String
sInput = sInput.Replace("%", "")
Dim ret_GBKDecode As String = ""
Dim sLen As Integer = sInput.Length
Dim n As Integer = sLen \ 2
Dim sBytes(0 To n - 1) As Byte
'转化为字节码
For i As Integer = 1 To n
sBytes(i - 1) = CByte("H" sInput.Substring(2 * i - 2, 2))
Next
'将字节码转化为字符串
ret_GBKDecode = System.Text.Encoding.Default.GetString(sBytes)
Return ret_GBKDecode
End Function