How to write from arduino to Vdip with high speed?

How can I convert an analog signal from an EKG project into a digital form and after that to write it in a memory stick via VDIP module?.I need to write it at high speed,I think(min.400 samles/sec) in order to get accurate numbers in memory stick.THX!

400Hz doesn't seem that fast - how much data (in bytes) do the samples represent?

I checked the analog signal from EKG with Picoscope and it's all right.Picoscope allows me to capture a period of signal and to save it in *.txt file.I saved one period and after that I made a graph in Excel from that saved file.X-axe is for time;y-axe is for voltage.In one period about 1.000.000µs=1s ,I got 12207 values in mV for my graph

how much data (in bytes) do the samples represent?

How many bytes are there per sample?
How many channels?

I got 1 channel only to measure from analog in,just the output of ekg board.Every sample has 8 characters and there are only numbers.I need to write many samples/sec(400+,don't know exactly)

OK, sorry, I misread your post - I thought you were using the Picoscope to capture the data. OK, if you're using the Arduino to do the analogue capture, then you're limited to 10 bits anyway, so assume they're stored unpacked, that's two bytes per sample, so you've only got to write 800 bytes per second.

Well I don’t know how can I write so fast.I think I should modify something about RCS an CTS.I have an example of code which writes 1 sample/sec and has RCS and CTS connected each other.

I have an example of code

Sharing it would help

Saw it here http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1243370818/5

the logger should read the sensor and write the value about once every second

That's what all those big delays are doing.

But if I take out these delays I lose information,because arduino will send fast but vdip will not process it so fast.I think this problem can be solved with some conditions about RCS and CTS,but don't know how :(