VB and PLC communication applications, problems: to accept the information can't echo to text2,-CodePudding

 Private Sub MSComm1_OnComm () 

Dim temp () As Byte 
Dim RCV () As Byte 
Dim rcvlenth As Integer 
Rcvlenth=1 

If Command2. Caption="stop accepting" Then 
The Select Case CommEvent 
Case comEvReceive 
Temp=MSComm1. Input 
ReDim Preserve temp (UBound (temp)) As Byte 
For I=LBound (temp) To UBound (temp) 
Rcvlenth=rcvlenth + 1 
RCV (I)=temp (I) 
Next I 

ReDim Preserve RCV (rcvlenth) As Byte 
For I=LBound (RCV) To UBound (RCV) 
Text2=Text2 & amp; STR $(RCV) (I) & amp; "
"Next I 
End the Select 
End the If 

MSComm1. InBufferCount=0 
MSComm1. OutBufferCount=0 

End Sub

Code as above, please help to look at thank you ~ ~

CodePudding user response:

Temp=MSComm1. Input
ReDim Preserve temp (UBound (temp)) As Byte

Suppose you first sentence has been accepted to the data, the second sentence redefine what length for?
Besides, it with the as redim Byte, it can only change the length, can't change the type of the (even before and the definition of the same type)

CodePudding user response:

reference 1st floor WallesCai response:

temp=MSComm1. Input
ReDim Preserve temp (UBound (temp)) As Byte

Suppose you first sentence has been accepted to the data, the second sentence redefine what length for?
Besides, it with the as redim Byte, it can only change the length, can't change the type (even before the definition of the same type) and

ReDim Preserve function is redefined, but keep the contents of the array before, only can extend the length of the array,

In Case comEvReceive set breakpoints here, whether can you stop?
Whether set mscomm1. Rthreshold=1 (or other non-zero values), you must not set, because I set up,,,
In addition in the first cycle
Rcvlenth=rcvlenth + 1
RCV (I)=temp (I)
RCV array is not defined here,

CodePudding user response:

 Dim temp As the Variant 
Dim RCV () As Byte 
Dim rcvlenth As Integer 
Rcvlenth=1 

If Command2. Caption="stop accepting" Then 
The Select Case CommEvent 
Case comEvReceive 
Temp=MSComm1. Input 
Rcvlenth=UBound (temp) 
Redim RCV (rcvlenth) 
For I=0 To rcvlenth 
RCV (I)=temp (I) 
Next I 

For I=0 To rcvlenth 
Text2=Text2 & amp; CStr (RCV) (I) & amp; "
"Next I 
End the Select 
End the If

CodePudding user response:

Thanks for your help, the last research down PLC loopback format might be the problem, first the VB100, until VB102 are bytes, and the first character and so on, VB103 real data area began to special thanks of123 great god, and two post to answer and give me great help. Thanks