vb.net - ACR122u help in reading the card - 


private sub read(sender object, e eventargs) handles mybase.load          dim readercount integer     dim readercount integer     dim ctr integer     dim sreaderlist string     dim ctr integer     dim sreaderlist string       ctr = 0 255     sreaderlist = sreaderlist + vbnullchar      next      readercount = 255      ' 1. establish context , obtain hcontext handle     retcode = modwinscard.scardestablishcontext(modwinscard.scard_scope_user, 0, 0, hcontext)       ' 2. list pc/sc card readers installed in system     retcode = modwinscard.scardlistreaders(hcontext, "", sreaderlist, readercount)        ' load available readers     call loadlisttocontrol(cbreader, sreaderlist)     cbreader.selectedindex = 0      if connactive         retcode = modwinscard.scarddisconnect(hcard, modwinscard.scard_unpower_card)     end if      ' shared connection     retcode = modwinscard.scardconnect(hcontext, cbreader.selecteditem.tostring(), modwinscard.scard_share_shared, modwinscard.scard_protocol_t0 or modwinscard.scard_protocol_t1, hcard, protocol)      connactive = true       connect()  end sub  public sub connect()      dim tmpstr string     dim indx integer       validats = false     call clearbuffers()     sendbuff(0) = &hff                              ' cla     sendbuff(1) = &hca                              ' ins       sendbuff(3) = &h0                               ' p2     sendbuff(4) = &h0                               ' le : full length      sendlen = sendbuff(4) + 5     recvlen = &hff      retcode = sendapduanddisplay(3)      if retcode <> modwinscard.scard_s_success          exit sub      end if       indx = 0 (recvlen - 3)          tmpstr = tmpstr + microsoft.visualbasic.right("00" & hex(recvbuff(indx)), 2) + " "      next indx      carduid = tmpstr      attendace_menu.show()     me.hide()  end sub

i need code. want read uid of smart card not when loading form when remove card , insert again. reads card when load form. have no idea since i'm new programming , project school.

you can use winscard library's scardgetstatuschange function observe changes via background worker thread.


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