vb串口接收数据的奇怪问题

Like_328 2009-06-02 03:35:01

我现在做一个简单串口通信的小测试,遇到一奇怪问题,一直想不通,望各位帮忙看一下,代码如下:
Private Sub Form_Load()
With MSComm1
.CommPort = 1
.Settings = "38400,n,8,1"
.OutBufferCount = 0
.InBufferCount = 0
.InputMode = 1
.RThreshold = 1
.SThreshold = 0
.OutBufferSize = 512
.InBufferSize = 1024
.InputLen = 0
.PortOpen = True
End With
End Sub
Private Sub MSComm1_OnComm()
Dim I As Integer
Dim strbuff As String
Dim indata As String
Dim inbte() As Byte
' Dim reclen As Integer
Select Case MSComm1.CommEvent
Case 2
strbuff = MSComm1.Input
' reclen = MSComm1.InBufferCount
inbte() = strbuff
For I = 0 To UBound(inbte)
If Len(Hex(inbte(I))) = 1 Then
indata = indata & "0" & Hex(inbte(I))
Else
indata = indata & Hex(inbte(I))
End If
Next I

Text1.Text = indata
End Select
End Sub
我用串口调试助手发送数据,把收到的数据显示在Text中,以十六进制发送
比如发送:A5 67 35 31 31 30 90 01 03 A0
但Text中只收到了01 03 A0
如果发送时把01 03 A0去掉,就可以收到了A5 67 35 31 31 30 90
我试过好多次都是这样,好像一次最多只能接收8位数似的
望高手看一下问题出在哪了

...全文

237 13 打赏收藏转发到动态举报

写回复

用AI写文章

13 条回复

切换为时间正序

请发表友善的回复…

发表回复

of123 2009-06-03

打赏
举报

Private Sub Form_Load()
With MSComm1
.CommPort = 1
.Settings = "38400,n,8,1"
.OutBufferCount = 0
.InBufferCount = 0
.InputMode = comInputModeBinary
.RThreshold = 10
.SThreshold = 0
.OutBufferSize = 512
.InBufferSize = 1024
.InputLen = 0
.PortOpen = True
End With
End Sub
Private Sub MSComm1_OnComm()
Dim I As Integer
Dim strbuff As Variant
Dim indata As String
Dim inbte() As Byte

Select Case MSComm1.CommEvent
Case 2
strbuff = MSComm1.Input
inbte = strbuff
For I = 0 To UBound(inbte)
indata = indata & Right("0" & Hex(inbte(I)), 2)
Next I

Text1.Text = indata
End Select
End Sub

zdingyun 2009-06-03

打赏
举报

串口通信线的接法:
2个RS232口间
2-3
3-2
5-5
连接
各自RS232口
4-6
7-8
短接
上述做法不考虑握手.

Like_328 2009-06-03

打赏
举报

我试了一下还是不行,第一次只收到前面8位,再发下一组数据时,先收到的是第一次没接收完的数据

simon__sun 2009-06-02

打赏
举报

.Settings = "38400,n,8,1" 改成 .Settings = "9600,n,8,1" 试试

贝隆 2009-06-02

打赏
举报

我也试了一下，楼主的代码能用
给你一个带源码的串口调试器，你单步调试一下看看。
http://download.csdn.net/source/1262066

zdingyun 2009-06-02

打赏
举报

LZ:你的代码没有问题,请查找其它方面的原因,串口助手与PC机的VB代码是否设置一致.此外你的通信线是如何接的?

Option Explicit

    Dim indata As String

Private Sub Form_Load()

    With MSComm1

        .CommPort = 1

        .Settings = "38400,n,8,1"

        .OutBufferCount = 0

        .InBufferCount = 0

        .InputMode = comInputModeBinary

        .RThreshold = 1

        .SThreshold = 0

        .OutBufferSize = 512

        .InBufferSize = 1024

        .InputLen = 0

        .PortOpen = True

    End With

End Sub

Private Sub MSComm1_OnComm()

    Dim I As Integer

    Dim strbuff As String

    Dim inbte() As Byte

    Select Case MSComm1.CommEvent

        Case 2

            strbuff = MSComm1.Input

            inbte() = strbuff

            For I = 0 To UBound(inbte)

                If Len(Hex(inbte(I))) = 1 Then

                  indata = indata & "0" & Hex(inbte(I))

                Else

                  indata = indata & Hex(inbte(I))

                End If

            Next I

            Text1.Text = indata

    End Select

End Sub