首先将需要读取的PLC内部元件的地址找到，主要内部元件地址如下：
D: PLC-Address*2+1000H;
T: PLC-Address+00C0H;
C: PLC-Address*2+01C0H;
S: PLC-Address*3;
M: PLC-Address*2+0100H;
Y: PLC-Address+00A0H;
X: PLC-Address+0080H;(只能读不能写，输入寄存器必须由外部信号驱动)
PLC-Address元件是指最低位开始后的第N个元件的位置。
一、VC与PLC的串口通讯主要操作：
1、对位元件和字元件状态读操作；
操作对象元件：PLC内部的X、Y、M、S、T、C、D元件
命令通用格式： STX CMD0 ADD LEN EXT CHK
意义： 起始符 读命令 元件起始位 个数 停止符 校验码
数字代码格式： 0X02 0X30 …… …… 0X03 ……
0x30是读操作指令；
ADD是读位元件或字元件的4位起始地址，高位先发，低位后发，以ASCII码的格式发送；
LEN是一次读取位元件或字元件的个数，最多可以读取0xff个字节的元件，也是以ASCII码的形式发送；
CHK是两位和校验，将CMD0,ADD,LEN,EXT三项进行和累计，将和累计的最低两位转化成ASCII，高位先发，低位后发。
在发完上述命令格式代码后，就可以直接读取PLC响应返回的信息，
响应信息格式：STX DATA EXT CHK
意义： 起始符 接收的数据 停止符 校验码
数字代码格式：0x02 …… 0x03 ……
DATA为我们需要读取的数据；
需要注意的是：读取DATA数据时遵循低位先发，高位后发的原则，所以我们解析数据的时候需要注意高低位的转换。
CHK则为DATA，EXT两项的和累计的最后两位转化为ASCII。
2、位元件和字元件状态写操作；
操作对象元件：PLC内部的XYMSTCU元件
命令通用格式：STX CMD1 ADD LEN DATA EXT CHK
意义： 起始符 读命令 元件起始位 个数 写入的数据 停止符 校验码
数字代码格式：0X02 0X31 …… 0X03 ……
0x031是写操作指令；
DATA是待写入PLC缓冲区的数据，低位先发，高位后发，以ASCII码的形式发送；
其他和读指令一样，此处不再重复；
发送后返回值为06，表示写入成功；
返回值为15，表示写入失败；
数据通讯举例：
例1：读D0的值
D0的内部地址为1000H=31H 30H 30H 30H
LEN表示我们需要读字节的个数，0-7为一个字节，D0占两个字节，所以LEN=30H 32H.
计算CHK校验码=CMD0+ADD+LEN+EXT
=30H+31H+30H+31H+30H+30H+32H+03H=157H
所以校验码为35H 37H.
得到完整的数字命令格式为：02H 30H 31H 30H 30H 30H 30H 32H 03H 35H 37H
将这段数字代码发送给PLC，
返回代码：02H 30H 30H 30H 30H 03H 43H 33H
得到数据段DATA为30H,31H,30H,30H=0001B（低位先发，高位后发）=1D
至此得到D0=1.
完成IPC读取PLC内部数据的全部过程。
IO通讯举例：
例2：读取Y1的值
Y1的内部地址是00A0=30H 30H 41H 30H，表示的意思是Y7-Y0的地址，Y1只是其中的一个位。
LEN因为00A0只有一个字节，所以可以去LEN=01D=30H 31H;
计算CHK校验码=36H 35H;
得到完成的数字代码为：02H 30H 30H 30H 41H 30H 30H 31H 03H 36H 35H;
返回代码：02H 30H 32H 03H 36H 35H
数据段为：30H 32H=02D=0010B
从Y7-Y0低往高排列可以知，Y1现在是状态值为1；
如果这里取LEN=2D=30H 32H
发送代码：02H 30H 30H 30H 41H 30H 30H 32H 03H 36H 36H;
返回代码：02H 30H 32H 30H 30H 03H 43H 35H
数据段为：30H 32H 30H 30H=0002B(低位先发，高位后发)=2D
从Y7-Y0低往高排列可以知，Y1现在是状态值为1；
注意：全部过程中，PLC内部程序不需要做任何程序编写。
三、PLC读取IPC数据时：
数据通讯举例：
例1：PLC读取IPC内部参数X的值。
思路：1、先将X的值转化成数字代码形式。
2、再讲X的值发送写入PLC内部数据寄存器中；
3、然后PLC直接读取这个数据寄存器的数据。
设：X=2;数据写入PLC内部数据寄存器D0中
则DATA=X=2=0010H=31H 30H 30H 30H（低位先发，高位后发）;
ADD=31H 30H 30H 30H;
LEN=02D=30H 32H.;（D为10进制；H为16进制）
CHK=CMD1+ADD+LEN+DATA+EXT；
=31H+31H+30H+30H+30H+30H+32H+31H+30H+30H+30H+03H=218H
则校验码为：31H 38H
完整的数字代码为：02H 31H 31H 30H 30H 30H 30H 32H 31H 30H 30H 30H 03H 31H 38H
返回值为06表示写入成功，PLC直接读取D0里面的数据即可。
完成PLC读取IPC数据。
当然这只是即时的读取，如果需要可控性的话，需要增加自定义读取和发送标志位，多加个数据用来表示控制字节用。
IO通讯举例：
例2：IPC置位PLC内部位元件Y1
思路：1、确定Y1地址（读操作已说明）；
2、就于写入的原理，需要先读取00A0的值；
3、将读取的值与0010进行&运算，确定Y1是否为0；
4、为0，则将读取值与0010进行或运算，再将得到的值转为数字代码形式发送给PLC； 为1，则表示内部Y1已经为1，不需要重复置位；
5、写入成功后返回06；
编写VC程序时需要用到以上思路；
这里我们假设我们只是写入Y1=1来操作：
Y1的PLC内部地址为：00A0H；表示Y7-Y0的地址，Y1只是其中一个位；
LEN取2个字节16位=30H 32H;
写入数据：00A0表示的是Y7-Y0 8个位，需要Y1为1，写入00000010B=02H,但是LEN为2，表示2个字节，所以需要写入0002H转化为30H 32H 30H 30H(低位先发，高位后发)；
完整代码：02H 31H 30H 30H 41H 30H 30H 32H 30H 32H 30H 30H 03H 32H 39H
返回：06写入成功。
四、数据通讯VC代码编写分析实例：
例1：将IPC端3个数据：
X=1003.5；Y=-4500；Z=-3.1456
写入PLC中
代码编写步骤：
1、将XYZ分别转化成整数，然后保存其小数位数，这里将XYZ分别都乘以10的N次方，直到其不在 -32767-32767范围后分别保存乘以10的个数在N1，N2，N3中；
从而得到 X=10035 ; N1=1;
Y=-4500; N2=0;
Z=31456; N3=4;
2、将X、Y、Z、N1、N2、N3分别转换成16进制；
3、再转化为16进制ASCII码；
4、将得到的16进制ASCII码按照X、N1、Y、N2、Z、N3的顺序排列进counts[35]数组中；
5、计算校验码;
6、将数据counts[35]每个数转化为对应的两个ASCII码值保存于counts_ascii[70]中；
例如：“35”转化为“3”和“5”；
7、将ASCII码转化为字符串代码保存于a2[70],累加排列输出；
例如：“3”的字符串代码为48+3=51；
8、返回值06，表示写入成功。
例2：读取PLC内部数据X、Y、Z的值
（读取D0-D5的数据）
代码编写步骤：(思路与上例一样)
1、将固定读取的数字代码发送给PLC，
固定读取D0-D5的数字代码为：02H 30H 31H 30H 30H 30H 30H 43H 03H 36H 37H
2、发送成功后，则有数据信息反馈；不成功则返回15；
3、将返回的窗口输出字符串依次保存在字符串数组char s1[84]中；
4、将数组s1转化为数字保存在数据b中；类似：字符串数字51=“3”；
5、将数组b转为16进制ASCII，再转化为10进制保存在数组c中；
例如：“3”“5”=3*10+5=35；再如：35H=5D；
6、将数组c转为2进制，方便判断正负数和后期运算，保存在数值c2中；
7、判断正负数，设立标志位flog；
如果为负数，则将其二进制取反加1后转化为10进制整数；
如果不为负数，则直接转化为10进制整数；
8、得到的数分别保存在D0、D1、D2、D3、D4、D5中（IPC内部变量区别开PLC内部数据寄存器）；
自定义运算；
可以得到 X=D0/(10^D1);//D0除以10的D1次方
Y=D2/(10^D3);
Z=D4/(10^D5);
'Private Declare Sub Sleep Lib "kernel32" (ByVal dwseconds As Long) '延时函数毫秒
Dim ik As Integer
Dim str_write() As Byte '发送数组
Dim str_val(0 To 5) As Byte
Dim 非读操作 As Boolean '此位为真是表示有非读命令等待执行，那么暂停读命令，执行非读操作
Dim 何种非读操作 As Integer '此变量用来区分等待的是何种非读命令
Dim 读操作 As Boolean '此变量作用：当有非读命令而读操作的接收处理没有完成时，先完成读命令的接收处理
Dim i As Integer '此变量作用：读操作时因为读的类型不一样，所以每次读一种（如X），然后下一次根据i的数值判断是应该读那种类型。
Dim 第一次 As Boolean
Dim dz As Integer '元件操作地址
Dim lie As Byte, lie1 As Byte, lie2 As Byte '元件操作类型
Dim SRet As Byte
Private Sub Command1_Click(Index As Integer) '写VW0---VW30
Dim shuju As String
Dim shuju1 As String
Dim shuju2 As String
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非读操作 = True
何种非读操作 = 3
shuju = Right("0000" + Hex(Text4(Index).Text), 4)
shuju1 = ("&H" & Mid(shuju, 1, 2))
shuju2 = ("&H" & Mid(shuju, 3, 2))
ReDim str_write(0 To 38) As Byte '重新定义数组
str_write(0) = &H68
str_write(1) = &H21
str_write(2) = &H21
str_write(3) = &H68
str_write(4) = &H2
str_write(5) = &H0
str_write(6) = &H6C
str_write(7) = &H32
str_write(8) = &H1
str_write(9) = &H0
str_write(10) = &H0
str_write(11) = &H0
str_write(12) = &H0
str_write(13) = &H0
str_write(14) = &HE
str_write(15) = &H0
str_write(16) = &H6
str_write(17) = &H5 '写
str_write(18) = &H1
str_write(19) = &H12
str_write(20) = &HA
str_write(21) = &H10
str_write(22) = &H2
str_write(23) = &H0
str_write(24) = &H2
str_write(25) = &H0
str_write(26) = &H1
str_write(27) = &H84
str_write(28) = &H0
str_write(29) = &H0
str_write(30) = (Index * 2 * 8) Mod 256
str_write(31) = &H0
str_write(32) = &H4
str_write(33) = &H0
str_write(34) = &H10
str_write(35) = shuju1
str_write(36) = shuju2
str_write(37) = SumChk(str_write)
str_write(38) = &H16
End Sub
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Private Sub Command2_Click(Index As Integer) 'S元件状态操作
非读操作 = True
何种非读操作 = 0
dz = Index
lie = &H4
lie1 = &H0
lie2 = &H7C
If Command2(Index).Caption = "S0." + Trim(Index) + "复位" Then
SRet = &H0
Else
SRet = &H1
End If
End Sub
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Private Sub Command3_Click(Index As Integer) 'M元件状态操作
非读操作 = True
何种非读操作 = 0
dz = Index
lie = &H83
lie1 = &H0
lie2 = &H7C
If Command3(Index).Caption = "M0." + Trim(Index) + "复位" Then
SRet = &H0
Else
SRet = &H1
End If
End Sub
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Private Sub Command4_Click(Index As Integer) 'V元件状态操作
非读操作 = True
何种非读操作 = 0
dz = Index
lie = &H84
lie1 = &H1
lie2 = &H6C
If Command4(Index).Caption = "V0." + Trim(Index) + "复位" Then
SRet = &H0
Else
SRet = &H1
End If
End Sub
Private Sub Command5_Click() '启动
非读操作 = True
何种非读操作 = 1
ReDim str_write(0 To 38) As Byte '重新定义数组
str_write(0) = &H68
str_write(1) = &H21
str_write(2) = &H21
str_write(3) = &H68
str_write(4) = &H2
str_write(5) = &H0
str_write(6) = &H7C
str_write(7) = &H32
str_write(8) = &H1
str_write(9) = &H0
str_write(10) = &H0
str_write(11) = &H0
str_write(12) = &H0
str_write(13) = &H0
str_write(14) = &H14
str_write(15) = &H0
str_write(16) = &H0
str_write(17) = &H28
str_write(18) = &H0
str_write(19) = &H0
str_write(20) = &H0
str_write(21) = &H0
str_write(22) = &H0
str_write(23) = &H0
str_write(24) = &HFD
str_write(25) = &H0
str_write(26) = &H0
str_write(27) = &H9
str_write(28) = &H50
str_write(29) = &H5F
str_write(30) = &H50
str_write(31) = &H52
str_write(32) = &H4F
str_write(33) = &H47
str_write(34) = &H52
str_write(35) = &H41
str_write(36) = &H4D
str_write(37) = SumChk(str_write)
str_write(38) = &H16
End Sub
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Private Sub Command6_Click() '停止
ReDim str_write(0 To 34) As Byte '重新定义数组
非读操作 = True
何种非读操作 = 2
str_write(0) = &H68
str_write(1) = &H1D
str_write(2) = &H1D
str_write(3) = &H68
str_write(4) = &H2
str_write(5) = &H0
str_write(6) = &H7C
str_write(7) = &H32
str_write(8) = &H1
str_write(9) = &H0
str_write(10) = &H0
str_write(11) = &H0
str_write(12) = &H0
str_write(13) = &H0
str_write(14) = &H10
str_write(15) = &H0
str_write(16) = &H0
str_write(17) = &H29
str_write(18) = &H0
str_write(19) = &H0
str_write(20) = &H0
str_write(21) = &H0
str_write(22) = &H0
str_write(23) = &H9
str_write(24) = &H50
str_write(25) = &H5F
str_write(26) = &H50
str_write(27) = &H52
str_write(28) = &H4F
str_write(29) = &H47
str_write(30) = &H52
str_write(31) = &H41
str_write(32) = &H4D
str_write(33) = SumChk(str_write)
str_write(34) = &H16
End Sub
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Private Sub Combo1_Click() '通讯口选择
Call CommSet '调用通讯口设置过程
End Sub
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Private Sub CommSet()
On Error GoTo err1 '此处作用：如果您选择了电脑中不存在的通讯口，则提示“无效的通讯口”
If MSComm1.PortOpen = True Then MSComm1.PortOpen = False
MSComm1.CommPort = Val(Mid(Combo1.Text, 4, 1))
MSComm1.Settings = "9600,e,8,1"
MSComm1.InBufferCount = 0
MSComm1.OutBufferCount = 0
MSComm1.InputLen = 0
MSComm1.RThreshold = 0
MSComm1.InputMode = comInputModeBinary
MSComm1.PortOpen = True
第一次 = False
非读操作 = False
str_val(0) = &H10
str_val(1) = &H2
str_val(2) = &H0
str_val(3) = &H5C
str_val(4) = &H5E
str_val(5) = &H16
Timer1.Enabled = True
Exit Sub
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err1:
MsgBox Err.Description '错误提示
End Sub
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Private Sub Form_Load()
Dim g As Integer
On Error GoTo err1 '此处作用：如果您选择了电脑中不存在的通讯口，则提示“无效的通讯口”
For g = 1 To 9 '添加通讯选择
Combo1.AddItem "Com" & Trim$(Str$(g))
Next g
MSComm1.CommPort = 1
MSComm1.Settings = "9600,e,8,1"
MSComm1.InBufferCount = 0
MSComm1.OutBufferCount = 0
MSComm1.InputLen = 0
MSComm1.RThreshold = 0
MSComm1.InputMode = comInputModeBinary
MSComm1.PortOpen = True
第一次 = False
非读操作 = False
str_val(0) = &H10
str_val(1) = &H2
str_val(2) = &H0
str_val(3) = &H5C
str_val(4) = &H5E
str_val(5) = &H16
Timer1.Enabled = True
Exit Sub
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err1:
MsgBox Err.Description '错误提示
End Sub
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Private Sub Form_Unload(Cancel As Integer)
MSComm1.InBufferCount = 0
MSComm1.OutBufferCount = 0
If MSComm1.PortOpen = True Then MSComm1.PortOpen = False
End
End Sub
Private Function SumChk(Dats) As Byte '校验和计算
Dim l As Integer, j As Integer
Dim Temp_FCS As Variant
l = UBound(Dats)
For j = 4 To l 'Len 函数，返回 Long，其中包含字符串内字符的数目，或是存储一变量所需的字节数
Temp_FCS = Temp_FCS + str_write(j)
Next j
SumChk = Temp_FCS Mod 256
End Function
Private Function dec2bin(Dats$) As String '转换成二进制
Dim bin8
Dim bin4
Dim bin2
Dim bin1
Dim bin16
Dim bin32
Dim bin64
Dim bin128
If Dats \ 128 >= 1 Then
bin128 = 1
Else
bin128 = 0
End If
If (Dats Mod 128) \ 64 >= 1 Then
bin64 = 1
Else
bin64 = 0
End If
If (Dats Mod 64) \ 32 >= 1 Then 'Mod用来对两个数作除法并且只返回余数
bin32 = 1
Else
bin32 = 0
End If
If (Dats Mod 32) \ 16 >= 1 Then
bin16 = 1
Else
bin16 = 0
End If
If (Dats Mod 16) \ 8 >= 1 Then '\ 运算符用来对两个数作除法并返回一个整数
bin8 = 1
Else
bin8 = 0
End If
If (Dats Mod 8) \ 4 >= 1 Then 'Mod用来对两个数作除法并且只返回余数
bin4 = 1
Else
bin4 = 0
End If
If (Dats Mod 4) \ 2 >= 1 Then
bin2 = 1
Else
bin2 = 0
End If
If Dats Mod 2 = 0 Then
bin1 = 0
Else
bin1 = 1
End If
bin128 = CStr(bin128) 'CStr 函数将一数值转换为 String
bin64 = CStr(bin64)
bin32 = CStr(bin32)
bin16 = CStr(bin16)
bin8 = CStr(bin8) 'CStr 函数将一数值转换为 String
bin4 = CStr(bin4)
bin2 = CStr(bin2)
bin1 = CStr(bin1)
dec2bin = bin128 + bin64 + bin32 + bin16 + bin8 + bin4 + bin2 + bin1
End Function
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Private Sub MSComm1_OnComm()
Dim rcv_array() As Byte
Dim rcv_len As Long
Dim read As String, read1 As String
Dim j As Integer
Dim wei(2) As String
If MSComm1.CommEvent = comEvReceive Then 'CommEvent的属性返回的值为comEvReceive时是发生了接收事件.
rcv_array = MSComm1.Input
If 第一次 = True Then '判断发送的是那一组
If Right("00" + Hex(rcv_array(0)), 2) <> "E5" Then '如果返回的不是E5，则重新发数据
Shape6.BackColor = &HC0&
MSComm1.RThreshold = 0
Timer1.Enabled = True
Timer2.Enabled = False
Text5 = "1"
Else '如果是E5，则发最后一组数据
If 非读操作 = True And 读操作 = False Then '如果是非读命令产生的接收事件
Select Case 何种非读操作
Case 0 '置/复位
MSComm1.RThreshold = 24
Case 1 'PLC启动
MSComm1.RThreshold = 20
Case 2 'PLC停止
MSComm1.RThreshold = 20
Case 3 '数值写入
MSComm1.RThreshold = 18
End Select
Else '如果是实时监控
Select Case i
Case 0 '读M0.0—M0.7
MSComm1.RThreshold = 28
Case 1 '读T0
MSComm1.RThreshold = 30
Case 2 '读V0.0—V0.7
MSComm1.RThreshold = 28
Case 3 '读输入
MSComm1.RThreshold = 29
Case 4 '读VW0—VW15
MSComm1.RThreshold = 59
Case 5 '读输出
MSComm1.RThreshold = 29
Case 6 '读S0.0—S0.7
MSComm1.RThreshold = 28
Case 7 '读C0
MSComm1.RThreshold = 30
End Select
End If '判断非读操作结束
MSComm1.InBufferCount = 0
MSComm1.OutBufferCount = 0
MSComm1.Output = str_val '发送命令
第一次 = False
Text5 = "2"
End If '判断返回的E5是否正确结束
Else '如果是第二组命令
rcv_len = UBound(rcv_array) '返回一个 Long 型数据，其值为指定的数维组可用的最大下标
For j = 0 To rcv_len
read = read & Right("00" + Hex(rcv_array(j)), 2)
Next j
If 非读操作 = True And 读操作 = False Then '如果是非读命令产生的接收事件
非读操作 = False '
Shape6.BackColor = &HC0&
MSComm1.InBufferCount = 0
MSComm1.OutBufferCount = 0
Timer1.Enabled = True
Else '如果是实时监控命令产生的接收事件
Select Case i
Case 0 '读M0.0—M0.7
read1 = Val("&H" + Mid(Right(read, 6), 1, 2))
wei(0) = dec2bin(read1) '调用十二进转二进制过程
For j = 0 To 7
If Mid(wei(0), 8 - j, 1) = "1" Then
Shape4(j).BackColor = &HC0&
Command3(j).Caption = "M0." + Trim(j) + "复位"
Else
Shape4(j).BackColor = &HE0E0E0
Command3(j).Caption = "M0." + Trim(j) + "置位"
End If
Next j
Case 1 '读T0
read1 = Val("&H" + Mid(Right(read, 8), 1, 4))
Text2.Text = read1 'T当前值显示
Case 2 '读V0.0—V0.7
read1 = Val("&H" + Mid(Right(read, 6), 1, 2))
wei(0) = dec2bin(read1) '调用十二进转二进制过程
For j = 0 To 7
If Mid(wei(0), 8 - j, 1) = "1" Then
Shape5(j).BackColor = &HC0&
Command4(j).Caption = "V0." + Trim(j) + "复位"
Else
Shape5(j).BackColor = &HE0E0E0
Command4(j).Caption = "V0." + Trim(j) + "置位"
End If
Next j
Case 3 '读输入
read1 = Mid(Right(read, 8), 1, 4)
wei(0) = dec2bin(Val("&H" + Mid(read1, 1, 2))) '调用十二进转二进制过程
wei(1) = dec2bin(Val("&H" + Right(read1, 2))) '调用十二进转二进制过程
wei(2) = wei(1) + wei(0)
For j = 0 To 15
If Mid(wei(2), 16 - j, 1) = "1" Then
Shape1(j).BackColor = &HC0&
Else
Shape1(j).BackColor = &HE0E0E0
End If
Next j
Case 4 '读VW0—VW15
read1 = Mid(Right(read, 68), 1, 64)
For j = 0 To 15
Text1(j).Text = Val("&H" + Mid(read1, 1 + j * 4, 4))
Next j
Case 5 '读输出
read1 = Mid(Right(read, 8), 1, 4)
wei(0) = dec2bin(Val("&H" + Mid(read1, 1, 2))) '调用十二进转二进制过程
wei(1) = dec2bin(Val("&H" + Right(read1, 2))) '调用十二进转二进制过程
wei(2) = wei(1) + wei(0)
For j = 0 To 15
If Mid(wei(2), 16 - j, 1) = "1" Then
Shape2(j).BackColor = &HC0&
Else
Shape2(j).BackColor = &HE0E0E0
End If
Next j
Case 6 '读S0.0—S0.7
read1 = Val("&H" + Mid(Right(read, 6), 1, 2))
wei(0) = dec2bin(read1) '调用十二进转二进制过程
For j = 0 To 7
If Mid(wei(0), 8 - j, 1) = "1" Then
Shape3(j).BackColor = &HC0&
Command2(j).Caption = "S0." + Trim(j) + "复位"
Else
Shape3(j).BackColor = &HE0E0E0
Command2(j).Caption = "S0." + Trim(j) + "置位"
End If
Next j
Case 7 '读C0
read1 = Val("&H" + Mid(Right(read, 8), 1, 4))
Text3.Text = read1 'C当前值显示
i = -1 '常规读取全部完成，从头开始，因为下面有一个+1命令，所以此处赋-1
End Select
i = i + 1 '进行下一个类型的常规读取
读操作 = False '读操作接收处理完成
Shape6.BackColor = &HC0&
Timer1.Enabled = True '进行下一个类型的常规读取
Timer2.Enabled = False
End If
End If '判断第一组发送命令结束
End If
End Sub
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Private Sub Timer1_Timer()
第一次 = True
MSComm1.RThreshold = 1 '因为PLC接收到写或是置位命令，只返回一个字符，所以设为1（RThreshold：定义接收缓冲区接收多少个字符后产生COMMFX_OnComm事件）
If 非读操作 = True Then '如果有非读命令存在
Select Case 何种非读操作
Case 0
ReDim str_write(0 To 37) As Byte '重新定义数组
str_write(0) = &H68
str_write(1) = &H20
str_write(2) = &H20
str_write(3) = &H68
str_write(4) = &H2
str_write(5) = &H0
str_write(6) = lie2 '类型
str_write(7) = &H32
str_write(8) = &H1
str_write(9) = &H0
str_write(10) = &H0
str_write(11) = &H0
str_write(12) = &H0
str_write(13) = &H0
str_write(14) = &HE
str_write(15) = &H0
str_write(16) = &H5
str_write(17) = &H5
str_write(18) = &H1
str_write(19) = &H12
str_write(20) = &HA
str_write(21) = &H10
str_write(22) = &H1
str_write(23) = &H0
str_write(24) = &H1
str_write(25) = &H0
str_write(26) = lie1 '存储器类型，01：V存储器 00：其它
str_write(27) = lie '读不同元件的代码
str_write(28) = &H0
str_write(29) = &H0
str_write(30) = dz
str_write(31) = &H0
str_write(32) = &H3
str_write(33) = &H0
str_write(34) = &H1
str_write(35) = SRet '置/复位
str_write(36) = SumChk(str_write)
str_write(37) = &H16
End Select
Else ' 如果没有非读命令则执行常规轮询
读操作 = True '置真的目的：当有非读命令而读操作的接收处理没有完成时，先完成读命令的接收处理
Select Case i
Case 0 '读M0.0—M0.7
ReDim str_write(0 To 32) As Byte '重新定义数组
str_write(0) = &H68
str_write(1) = &H1B
str_write(2) = &H1B
str_write(3) = &H68
str_write(4) = &H2
str_write(5) = &H0
str_write(6) = &H6C
str_write(7) = &H32
str_write(8) = &H1
str_write(9) = &H0
str_write(10) = &H0
str_write(11) = &H0
str_write(12) = &H0
str_write(13) = &H0
str_write(14) = &HE
str_write(15) = &H0
str_write(16) = &H0
str_write(17) = &H4 '读
str_write(18) = &H1
str_write(19) = &H12
str_write(20) = &HA
str_write(21) = &H10
str_write(22) = &H2 '读取位，字节，字，双字（1，2，4，8）
str_write(23) = &H0
str_write(24) = &H1 '以字节为单位，连续读取的字节数
str_write(25) = &H0
str_write(26) = &H0 '存储器类型，01：V存储器 00：其它
str_write(27) = &H83 '读不同元件的代码
str_write(28) = &H0
str_write(29) = &H0 '高位地址 地址转换地16进制 （字节号*8+位号）\256
str_write(30) = &H0 '低位地址 地址转换地16进制 （字节号*8+位号）Mod 256
str_write(31) = SumChk(str_write)
str_write(32) = &H16
Case 1 '读T0
ReDim str_write(0 To 32) As Byte '重新定义数组
str_write(0) = &H68
str_write(1) = &H1B
str_write(2) = &H1B
str_write(3) = &H68
str_write(4) = &H2
str_write(5) = &H0
str_write(6) = &H7C
str_write(7) = &H32
str_write(8) = &H1
str_write(9) = &H0
str_write(10) = &H0
str_write(11) = &H0
str_write(12) = &H8 '&H8
str_write(13) = &H0
str_write(14) = &HE
str_write(15) = &H0
str_write(16) = &H0
str_write(17) = &H4 '读
str_write(18) = &H1
str_write(19) = &H12
str_write(20) = &HA
str_write(21) = &H10
str_write(22) = &H1F '读取位，字节，字，双字（1，2，4，8）
str_write(23) = &H0
str_write(24) = &H1 '读取数据个数
str_write(25) = &H0
str_write(26) = &H0 '存储器类型，01：V存储器 00：其它
str_write(27) = &H1F '读不同元件的代码
str_write(28) = &H0
str_write(29) = &H0 '高位地址 地址转换地16进制 （字节号*8+位号）\256
str_write(30) = &H0 '低位地址 地址转换地16进制 （字节号*8+位号）Mod 256
str_write(31) = SumChk(str_write)
str_write(32) = &H16
Case 2 '读V0.0—V0.7
ReDim str_write(0 To 32) As Byte '重新定义数组
str_write(0) = &H68
str_write(1) = &H1B
str_write(2) = &H1B
str_write(3) = &H68
str_write(4) = &H2
str_write(5) = &H0
str_write(6) = &H6C
str_write(7) = &H32
str_write(8) = &H1
str_write(9) = &H0
str_write(10) = &H0
str_write(11) = &H0
str_write(12) = &H0
str_write(13) = &H0
str_write(14) = &HE
str_write(15) = &H0
str_write(16) = &H0
str_write(17) = &H4 '读
str_write(18) = &H1
str_write(19) = &H12
str_write(20) = &HA
str_write(21) = &H10
str_write(22) = &H2 '读取位，字节，字，双字（1，2，4，8）
str_write(23) = &H0
str_write(24) = &H1 '读取数据个数
str_write(25) = &H0
str_write(26) = &H1 '存储器类型，01：V存储器 00：其它
str_write(27) = &H84 '读不同元件的代码
str_write(28) = &H0
str_write(29) = &H0 '高位地址 地址转换地16进制 （字节号*8+位号）\256
str_write(30) = &H0 '低位地址 地址转换地16进制 （字节号*8+位号）Mod 256
str_write(31) = SumChk(str_write)
str_write(32) = &H16
Case 3 '读输入
ReDim str_write(0 To 32) As Byte '重新定义数组
str_write(0) = &H68
str_write(1) = &H1B
str_write(2) = &H1B
str_write(3) = &H68
str_write(4) = &H2
str_write(5) = &H0
str_write(6) = &H6C
str_write(7) = &H32
str_write(8) = &H1
str_write(9) = &H0
str_write(10) = &H0
str_write(11) = &H0
str_write(12) = &H0
str_write(13) = &H0
str_write(14) = &HE
str_write(15) = &H0
str_write(16) = &H0
str_write(17) = &H4 '读
str_write(18) = &H1
str_write(19) = &H12
str_write(20) = &HA
str_write(21) = &H10
str_write(22) = &H2 '读取位，字节，字，双字（1，2，4，8）
str_write(23) = &H0
str_write(24) = &H2 '读取数据个数
str_write(25) = &H0
str_write(26) = &H0 '存储器类型，01：V存储器 00：其它
str_write(27) = &H81 '读不同元件的代码
str_write(28) = &H0
str_write(29) = &H0 '高位地址 地址转换地16进制 （字节号*8+位号）\256
str_write(30) = &H0 '低位地址 地址转换地16进制 （字节号*8+位号）Mod 256
str_write(31) = SumChk(str_write)
str_write(32) = &H16
Case 4 '读VW0—VW15
ReDim str_write(0 To 32) As Byte '重新定义数组
str_write(0) = &H68
str_write(1) = &H1B
str_write(2) = &H1B
str_write(3) = &H68
str_write(4) = &H2
str_write(5) = &H0
str_write(6) = &H6C
str_write(7) = &H32
str_write(8) = &H1
str_write(9) = &H0
str_write(10) = &H0
str_write(11) = &H0
str_write(12) = &H0
str_write(13) = &H0
str_write(14) = &HE
str_write(15) = &H0
str_write(16) = &H0
str_write(17) = &H4 '读
str_write(18) = &H1
str_write(19) = &H12
str_write(20) = &HA
str_write(21) = &H10
str_write(22) = &H2 '读取位，字节，字，双字（1，2，4，8）
str_write(23) = &H0
str_write(24) = &H20 '以字节为单位，连续读取的字节数
str_write(25) = &H0
str_write(26) = &H1 '存储器类型，01：V存储器 00：其它
str_write(27) = &H84 '读不同元件的代码
str_write(28) = &H0
str_write(29) = &H0 '高位地址 地址转换地16进制 （字节号*8+位号）\256
str_write(30) = &H0 '低位地址 地址转换地16进制 （字节号*8+位号）Mod 256
str_write(31) = SumChk(str_write)
str_write(32) = &H16
Case 5 '读输出
ReDim str_write(0 To 32) As Byte '重新定义数组
str_write(0) = &H68
str_write(1) = &H1B
str_write(2) = &H1B
str_write(3) = &H68
str_write(4) = &H2
str_write(5) = &H0
str_write(6) = &H6C
str_write(7) = &H32
str_write(8) = &H1
str_write(9) = &H0
str_write(10) = &H0
str_write(11) = &H0
str_write(12) = &H0
str_write(13) = &H0
str_write(14) = &HE
str_write(15) = &H0
str_write(16) = &H0
str_write(17) = &H4 '读
str_write(18) = &H1
str_write(19) = &H12
str_write(20) = &HA
str_write(21) = &H10
str_write(22) = &H2 '读取位，字节，字，双字（1，2，4，8）
str_write(23) = &H0
str_write(24) = &H2 '读取数据个数
str_write(25) = &H0
str_write(26) = &H0 '存储器类型，01：V存储器 00：其它
str_write(27) = &H82 '读不同元件的代码
str_write(28) = &H0
str_write(29) = &H0 '高位地址 地址转换地16进制 （字节号*8+位号）\256
str_write(30) = &H0 '低位地址 地址转换地16进制 （字节号*8+位号）Mod 256
str_write(31) = SumChk(str_write)
str_write(32) = &H16
Case 6 '读S0.0—S0.7
ReDim str_write(0 To 32) As Byte '重新定义数组
str_write(0) = &H68
str_write(1) = &H1B
str_write(2) = &H1B
str_write(3) = &H68
str_write(4) = &H2
str_write(5) = &H0
str_write(6) = &H6C
str_write(7) = &H32
str_write(8) = &H1
str_write(9) = &H0
str_write(10) = &H0
str_write(11) = &H0
str_write(12) = &H0
str_write(13) = &H0
str_write(14) = &HE
str_write(15) = &H0
str_write(16) = &H0
str_write(17) = &H4 '读
str_write(18) = &H1
str_write(19) = &H12
str_write(20) = &HA
str_write(21) = &H10
str_write(22) = &H2 '读取位，字节，字，双字（1，2，4，8）
str_write(23) = &H0
str_write(24) = &H1 '读取数据个数
str_write(25) = &H0
str_write(26) = &H0 '存储器类型，01：V存储器 00：其它
str_write(27) = &H4 '读不同元件的代码
str_write(28) = &H0
str_write(29) = &H0 '高位地址 地址转换地16进制 （字节号*8+位号）\256
str_write(30) = &H0 '低位地址 地址转换地16进制 （字节号*8+位号）Mod 256
str_write(31) = SumChk(str_write)
str_write(32) = &H16
Case 7 '读C0
ReDim str_write(0 To 32) As Byte '重新定义数组
str_write(0) = &H68
str_write(1) = &H1B
str_write(2) = &H1B
str_write(3) = &H68
str_write(4) = &H2
str_write(5) = &H0
str_write(6) = &H7C
str_write(7) = &H32
str_write(8) = &H1
str_write(9) = &H0
str_write(10) = &H0
str_write(11) = &H0
str_write(12) = &H12 '&H8
str_write(13) = &H0
str_write(14) = &HE
str_write(15) = &H0
str_write(16) = &H0
str_write(17) = &H4 '读
str_write(18) = &H1
str_write(19) = &H12
str_write(20) = &HA
str_write(21) = &H10
str_write(22) = &H1E '读取位，字节，字，双字（1，2，4，8）
str_write(23) = &H0
str_write(24) = &H1 '读取数据个数
str_write(25) = &H0
str_write(26) = &H0 '存储器类型，01：V存储器 00：其它
str_write(27) = &H1E '读不同元件的代码
str_write(28) = &H0
str_write(29) = &H0 '高位地址 地址转换地16进制 （字节号*8+位号）\256
str_write(30) = &H0 '低位地址 地址转换地16进制 （字节号*8+位号）Mod 256
str_write(31) = SumChk(str_write)
str_write(32) = &H16
End Select
End If
MSComm1.InBufferCount = 0
MSComm1.OutBufferCount = 0
MSComm1.Output = str_write '发送命令
ik = 0
Timer1.Enabled = False '等待接收处理结束后再进行下一次的命令发送
Timer2.Enabled = True
Text5 = "0"
Shape6.BackColor = &HE0E0E0
End Sub
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Private Sub Timer2_Timer()
ik = ik + 1
If ik > 3 And Timer1.Enabled = False Then
Timer1.Enabled = True
End If
End Sub
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------