用VB作为上位机,本来是用RS232实现串口通信的,但是由于RS232的通信距离短,现在希望改成485的~我上网查了下资料,知道232是全双工工作,485是半双工工作的,但是对于通信协议还是有点迷茫~现在我将我232的通信协议发上来,希望大神们帮我改一下适合于485的~而且我想知道如果485是半双工的,那么怎么控制他来开和关呢~请指教。。谢谢了!!原程序如下
Timer1.Enabled = TrueMSComm1.InBufferSize = 2
MSComm1.InBufferCount = 0
MSComm1.OutBufferCount = 0
MSComm1.InputMode = comInputModeBinary
MSComm1.CommPort = 3
MSComm1.Settings = "9600,N,8,1"
MSComm1.RThreshold = 24
MSComm1.InputLen = 24
MSComm1.OutBufferSize = 1
Timer1.Interval = 20
Timer1.Enabled = TrueMSComm1.InBufferSize = 2
MSComm1.InBufferCount = 0
MSComm1.OutBufferCount = 0
MSComm1.InputMode = comInputModeBinary
MSComm1.CommPort = 3
MSComm1.Settings = "9600,N,8,1"
MSComm1.RThreshold = 24
MSComm1.InputLen = 24
MSComm1.OutBufferSize = 1
Timer1.Interval = 20
为什么不行,你两台电脑一直在同时交换数据?不是一直,就是我先用VB的上位机设置一个温度值发给DSP,然后DSP就开始给我传送实时的温度值,期间需要设置缓冲什么的,我就是怕在DSP给我传送数据的时候我设置缓冲什么的会有冲突!