The IOCTL_SMARTCARD_TRANSMIT request transmits data to, and receives data from, the inserted smart card.

Major code


Input buffer

  • Irp->AssociatedIrp.SystemBuffer A pointer to an SCARD_IO_REQUEST structure followed by the data to transmit to the inserted smart card.

Input buffer length

  • Parameters.DeviceIoControl.InputBufferLength Contains the size of the structure plus the length of trailing data bytes (if any). The dwProtocol member must be set to the protocol that was previously selected, and the cbPciLength member must be set to the size of the SCARD_IO_REQUEST structure itself (usually eight bytes). The structure is used for future protocols. Data that will be transmitted to the card must immediately follow this structure.

Output buffer

Bytes buffer contains the result of the transmission. The buffer points to the SCARD_IO_REQUEST structure immediately followed by the data received.

  • Irp->AssociatedIrp.SystemBuffer Receives the result of the transmission. This buffer must also begin with an SCARD_IO_REQUEST structure. Any data that was received from the card must be stored immediately after the structure.

Output buffer length

  • Parameters.DeviceIoControl.OutputBufferLength Contains the length of the output buffer.

Status block

Irp->IoStatus.Status is set to one of the following values.

Value Meaning
STATUS_SUCCESS The transmission was successful.
STATUS_NO_MEDIA No smart card is detected in the reader.
STATUS_IO_TIMEOUT The operation timed out.
STATUS_INVALID_DEVICE_STATE The protocol in the header file does not match the smart card protocol that was previously selected.
STATUS_BUFFER_TOO_SMALL The output buffer is too small for the return data.
STATUS_DEVICE_POWERED_OFF The proximity radio control is off.


IOCTL_SMARTCARD_TRANSMIT transmits data from the client to the detected smart card in ISO7816-4 compliant APDU. These APDUs are interpreted with respect to the PC/SC specification (Section 4.3.7 has more detailed requirements on support for different NFC contactless tag formats). Because the NFP feature shares the same driver with the smart card, the card should be connected right after the discovery, no explicit connect for the ‘Transmit’ is needed.

Because the input buffer and the output buffer are pointing to the same memory area, the driver must avoid overwriting the input data. Use the smart card driver library to make sure that the input data is not overwritten.


Requirement Value
Header winsmcrd.h

See also

Near field communication (NFC) design guide

Smart card design guide