That I am using is this chip.
http://www.datasheetdirect.com/part/80C5...%252B.html

The scenario:

I have this module, FIM 5110. http://www.nitgen.com/eng/product/fim50Series.html

I have this trainer: http://www.kandh.com.tw/products_2.php?prod=124

This chip: http://www.datasheetdirect.com/part/80C5...%252B.html

I have connect the FIM module to Intel 8051 via serial interface correctly, I managed to power up this module and using a program called EvTools I can see that the connection is right and I can speak with FIM.

The main idea is to get a fingerprint using this device which controlled by 8051. The communication protocol of FIM module is here: http://www.nitgen.com.br/download/...0_Beta.pdf
If I manage to connect with this device I must take fingerprints and after that I must compare it and echo some message to display or somewhere else.

First of all, according to communication protocol to connect to this module I must sent this packet:
7E 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 (page 99 FIM Com_Prot.)

And if successfully received I must receive this Acknowledgement packet:
7E 00 00 00 01 00 00 00 01 00 00 00 0A 00 00 00 00 00 00 00 00 00 00 00 0C (page 100)

I make the code to sent this packet, with the help of this book http://8052.com/book/ which I bought.
I sent the packet and after that I receive the first byte (7E) and the last (0C). These two is appeared at one 7 segment display which is connected to P2. If you can see it at LED bar please visit here http://www.youtube.com/watch?v=wua-y6gso7Y
First I explain that the program does not work if the module is disconnected and if I connect it is works sending back the 7E byte and after 01. (01 it is because I have only one user in FIM's database)

Here is my problem, it seems that I am loosing the intermediate bytes. This is that I am not understanding and I want your help. Thank you all of you that you help me. I am not trying to extract the code from one of you, simply I need some help.

I have at my mind the scenario and that I am trying to be able to carry. Ι have test several time the code that I give above. Sorry for using the old 8051, but I had another opportunity at the moment.