Private void SenderValue ()//thread a 
{
If (WriteState=true)//found thread 2 when he found the data of the need to add send WriteState=true 
{
Xinchuan come in n serialPort1. Write (WriteStatestr) 
} 
N serialPort1. Write (balabla)//no data in this cycle trigger when the receive continuous processing data 

This theory? Why sometimes can not correctly written xinchuan came in, it's no use sending interval sleep? Thank you all for the first