c# - APDU Selecting specific file and reading binary data -

i'm trying read specific binary information smart card using pc/sc api in c#.

i want select specific file

00 a4 02 0c 02 05 20

and read binary data

00 b0 00 00 8f

as far know 5 bytes reading binary data in following order:

class, instruction, parameter 1, parameter 2, length

my first question in order select file array of 7 bytes is.

class,instruction, parameter 1, parameter 2, ?,?,?

my second question isocase , protocol should use each command.

following case , protocol seems work reading binary data confuses me since i'm not using smartcard , not rfid.

var apdu = new commandapdu(isocase.case2short,rfidreader.activeprotocol)

using pcsc; using pcsc.iso7816;

i overdid , overlooked important detail. file trying open subfile , not opened until parent opened.

it worked when opened files in correct order before reading binary data.

i didn't have set protocols , isocases. did transmit of bytes.

scardreader reader = new scardreader();  reader.transmit(bytestosend, ref responsebuffer);

And