Analysis of IEC104 Power protocol

Three remote: telemetry, tele-mail, remote control

The 104 statute is the Protocol of communication between the plant station and the distribution network Master station, with the Ethernet as the carrier, and the service mode is the balanced transmission.

The basic architecture is compared to the OSI model as shown below:

Session type: Send/No Answer (S1), Send/Confirm (S2), Send/Response (S3)

Frame format: Single-byte frames, fixed frames, variable frames

101 Fixed frame: Fixed length 5 bytes, with 0x10 as the startup character, with 0x16 as the end character, including link control domain, link address field, checksum ((Control domain + Address field)%256).

101 Variable Frame: the length is not fixed, with 0x68 as the start character, with 0x16 as the ending character, including length field, link control domain, link address field, checksum ((Control domain + address domain + Application data field)%256), Application data field. Repeat the start Word again after the length repeats.

104 Variable and fixed frames: The 0x68 is the startup character, immediately following the APDU length and 4 8-bit control fields, followed by the user data.

Link Control domain: Two directions defined separately, balanced and unbalanced, 1 bytes

Link address domain: Receiver ID, 1 bytes

104 vs. 101 variable frame comparison:

Application Protocol Control information (APDU) Definition:

Data frame type: I-format frame (numbering information xx), S-format frame (numbering monitor-down), U-format frame (unnumbered control 11)

Listening Port: 2404

Connection control: Both parties have the right to close

Timeout definition t2<t1<t0: Establish connection timeout (T0 30s): Reconnect Control Message Acknowledgement timeout (T1 15s): Send test frame Monitor message response Timeout T2<T1 (T2 10s): Send s to confirm frame long idle timeout t3>t1 heartbeat time (T3 20s): Send Test frame

K and W: Maximum number k, last confirmed number W. The sender reaches the K stop send, the receiver receives the W confirmation, the range 1-32767, the recommended w< K * 2/3,k is 12,w for 8

Application Protocol Control information (APCI) Definition:

Send receive ordinal storage in small terminal mode, low down byte.

Application Service Data Unit (ASDU) definition:

Identified by the data unit, one or more information body two parts

Common Type identification:

Transmission reason:

Message body address range:

Public address: That is the RTU address

Variable structure qualifier: Single 0/order 1, number of information bodies