串行口能发送数据，但读取不到

[tothehell]

能给下位机发送命令，但读取不到数据
用串口调试助手也如此

代码如下：


Private Sub Command1_Click()

Dim sts As String

If MSComm1.PortOpen = False Then MSComm1.PortOpen = True 'open the line

Call CMD_SEND("WRSTA") 'ＯＫ！下位机可以启动
Call STS_RD(sts) '读不进来数据，　ＳＴＳ＝＂＂

If sts = "OK" Then Text1.Text = "Start Measurement"

End Sub
Private Sub CMD_SEND(send_cmd As String)

Dim d$

d$ = send_cmd + Chr$(13)
MSComm1.Output = d$

End Sub
Private Sub STS_RD(ByRef status As String)

Dim a$, b$, d$
Dim L As Integer

Do
DoEvents
'Text1.Text = Text1.Text + "before input"
a$ = MSComm1.Input
'Text1.Text = Text1.Text + "after input"
b$ = Right(a$, 1)
d$ = d$ + a$
Loop Until (b$ = Chr$(13)) '陷入死循环

L = Len(d$)
status = Mid$(d$, 1, L - 1)

End Sub

[iland9876543210]

顶

[hohairen]

http://code.ddvip.com/view/11236896002031.html
串口编程-云台镜头控制系统
或许有用

[KissApple]

如果用串口调试助手也没办法收到数据的话可以考虑一下串口是否有问题,你机器上有几个串口?连接一下用串口调试助手测一下能否正常收发