'电子秤（电子天平）使用RS232C和PC串口进行通讯，本例使用应答型。'因为要使用DDE来控制此电子秤的开、关，所以加入了一个Timer来读取DDE信息，发现为开'关信息的时候直接向COM写入相应的信息。 '加入一个1000ms的定时器来定时向COM写入读取信息。'建立Form,LinkMode->1-Sourse,LinkTopic->自己定义'MSComm控件->mscommWeight，2个Timer控件->tmrOrderScan(200ms)，'tmrRead(1000ms)Option ExplicitPrivate strRecBuf As StringPrivate Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)Private Sub Form_Activate() Me.Hide '如果用在实时数据采集上，那么可以选择隐藏此界面End SubPrivate Sub Form_Load() '设置并打开串口 If mscommWeight.PortOpen = True Then mscommWeight.PortOpen = False mscommWeight.CommPort = 1 'COM1 If mscommWeight.PortOpen = False Then mscommWeight.PortOpen = True mscommWeight.Settings = "2400,n,8,1" mscommWeight.InputLen = 0 mscommWeight.RThreshold = 1 mscommWeight.InputMode = comInputModeText '接收为文本方式 End SubPrivate Sub mscommweight_OnComm() Select Case mscommWeight.CommEvent '发生OnComm事件 Case comEvReceive '接收到信息 strRecBuf = strRecBuf & mscommWeight.Input '接收信息 Case Else End Select If InStr(strRecBuf, "g") Then '发现接收完毕（检测到最后一个标志） lblWeight.Caption = Mid(strRecBuf, InStr(strRecBuf, ",") + 1, 10) '取数据位 strRecBuf = "" '清除接收变量 End IfEnd SubPrivate Sub tmrOrderScan_Timer() DoEvents Select Case lblSwitch.Caption Case "Action" '当接收到开关信息时 tmrWeight.Enabled = False '关闭读信息定时器 mscommWeight.Output = Chr(&H50) & Chr(&HD) & Chr(&HA) '发送开关机信息 lblSwitch.Caption = "" '接收信息复位 Sleep 200 '等待200ms tmrWeight.Enabled = True '重新打开读信息定时器 Case Else End SelectEnd SubPrivate Sub tmrWeight_Timer() mscommWeight.Output = Chr(&H51) & Chr(&HD) & Chr(&HA) '发送读信息End Sub
