VC++串口通信SetCommState函数阻塞卡死

链接
SetCommState的struct _DCB类型参数，其值
StopBits= 0,1,2对应的是1bit,1.5bits,2bits
ByteSize = 6, 7, 8时StopBits不能为1
ByteSize = 5时StopBits不能为2