I am sorry if I posted on the wrong thread. If it is wrong then please let me know where should I put.

I wrote the serial driver in DOS to access the smartcard through standard ISO-programmer But I have a problem. I need helps. Below is my setup:

Serial port Configuration:
8bit word length, 2 stop-bit and odd parity.
Fifo trigger=8bytes

Procedure:
1) Baud-rate=9600, toggle RTS-line to reset the card. I got the AnswerToReset response.
2) Change Baud-rate to 19200.
3) Send the packet header to card but there is no response from a card. I double check the packet header. It is correct.

I received the echo bytes that feed back from ISO-programmer for every bytes that I send to them. It is correct.
I don't get any errors on the line (parity, frame, break).
I looked at ISO7816, it said pin:C4 and C8 is RFU. What is the RFU?

If you know any information that could help then please let me know. I appreciate. Thanks.