SCardStatus

[DllImport("winscard.dll", SetLastError = true)]
public static extern int SCardStatus(
   IntPtr hCard,
   byte[] szReaderName,
   ref uint pcchReaderLen,
   out uint pdwState,
   out uint pdwProtocol,
   byte[] pbAtr,
   ref uint pcbAtrLen
);

Microsoft documentation: Link