Bluetooth COM latency - FlushFileBuffers?

I need to send 18 byte command strings via a Bluetooth serial port at a
regular interval (25 times per second). However, the driver caches the data
from my WriteFile calls and sends bigger chunks at seemingly random
intervals (about four times a second).

How can I tell the BT com port to flush out the data more often?

I tried to set the buffer size and call FlushFileBuffers to no avail. I am
hoping that you driver guys may know a way to convince the driver that I
shorter latency at the cost of throughput.

Any help is greatly appreciated!

Matthias


Windows XP SP2, Belkin F8T001 Bluetooth USB dongle, Promi ESD-02 Bluetooth
to serial module.

The code uses standard Win32 API CreateFile/WriteFile to \\.\COM15