PDUs (pynetdicom.pdu)

Protocol Data Units (PDUs) are the message formats exchanged between peer application entities within a layer. A PDU consists of protocol control information and user data and are constructed using mandatory fixed fields followed by optional variable fields that contain one or more items and/or sub-items.

The DICOM Upper Layer protocol consists of seven Protocol Data Units:

• A-ASSOCIATE-RQ PDU
• A-ASSOCIATE-AC PDU
• A-ASSOCIATE-RJ PDU
• P-DATA-TF PDU
• A-RELEASE-RQ PDU
• A-RELEASE-RP PDU
• A-ABORT-RQ PDU

PDUs should be encoded as binary data prior to being sent to a peer Application Entities using the encode() class method. Each encoded PDU has as its first byte value a corresponding PDU Type:

0x01 - A-ASSOCIATE-RQ

0x02 - A-ASSOCIATE-AC

0x03 - A-ASSOCIATE-RJ

0x04 - P-DATA-TF

0x05 - A-RELEASE-RQ

0x06 - A-RELEASE-RP

0x07 - A-ABORT

The encoding of DICOM Upper Layer PDUs is always Big Endian byte ordering.