Hi,
j'm currently developing a project using the silabs C8051F320 chip.
The board must sample the signal from 6 load cells and send the results to the PC via Rs232 interface or USB (using the built in USB hardware of the chip).

The board is working as slave : j mean it waits commands from the PC, executes them and sends back the results.

For my customer the goal is the achieve a 200 Hz sampling frequency, it means my board must be able to receive and execute 200 commands per second.

After some optimizations j found a time of about 5,5 milliseconds from the start of the command sent by PC and the end of trasmission of the result by my board (measured with a scope).
This with a baudrate of 56000 bps.

Unfortunately seems that windows adds a minimun of 3/4 milliseconds between reception of result and send of next command. Maybe the timing are too critical for windows!

The program running on PC side is developed in delphi using the VCL control CPORT. J tried both windows 98 /XP and get similar results.

My questions are :
1) The sampling frequency is too high for windows???
2) Increasing the baudrate of RS232 or using the USB interface will improve the frequency or windows cannot go beyond certain timings??
3) anybody tried something similar in other projects??

My english is not excellent , j hope j explained well my problem and thanks in advance :)

Massimo.