Thank you so much for your reply, Staphen !
i installed the OpenPDC on hard disk, i put the Mysql database on RAM disk and i use the AdoAdapter to save data to Mysql Database. (the RAM disk can be faster than the Hard disk from 10 to 70 times, i read this on some forum).
i tried to test with my system on some case like below:
1. only one PMU connected: the PMU work at 50 frames/second of Data Rate => the System work well.
2. with 2 PMUs connected: the first one work at 10 frames/second of Data Rate, and the second one work at 50 frames/second of Data Rate => the problem appear.
3. with 5 PMUs connected: all of 5 PMUs work at 10 frames/second of Data Rate => the system work well ( all of data is sent by AdoAdapter have been saved to the Mysql Database).
this is my situation.
Please help me to solve this problem.
Thanks in advance any help !