In telecommunications, Advanced Data Communication Control Procedures (or Protocol) (ADCCP) is a bit-oriented data link layer protocol developed by the American National Standards Institute. It is functionally equivalent to the ISO High-Level Data Link Control (HDLC) protocol.

Although the ISO and ANSI standards writers coordinated their work, so the differences between the standards are mainly editorial, there is one meaningful difference: ADCCP's definition of the basic subset required to implement balanced asynchronous mode includes the RSET frame, while HDLC makes it optional.

One major difference between the two is the unnumbered (U) format. When extended (7-bit) sequence numbers are used, I and S frames have two-byte control fields. Like early versions of HDLC, ADCCP specifies a 2-byte control field format with the P/F flag duplicated. Later HDLC specifications, in particular ISO/IEC 13239, changed that to specify that U frames have 1-byte control fields in all cases.

ADCCP control fields
First byteSecond byteDescription
0123456701234567
0N(S)P/FN(R)I frame, N(S) is a 3-bit send sequence number
10typeP/FN(R)S frame, N(R) is a 3-bit receive sequence number
11typeP/FtypeU frame
0N(S)P/FN(R)Extended I frame, N(S) is a 7-bit sequence number
10type—0—P/FN(R)Extended S frame, N(R) is a 7-bit sequence number
11typeP/FtypeP/F—0—Extended U frame (ADCCP only)

See also

  • Friend, George E.; Fike, John L.; Baker, H. Charles; Bellamy, John C. (1988). Understanding Data Communications (2nd ed.). Indianapolis: Howard W. Sams & Company. ISBN 0-672-27270-9.
  • . National Bureau of Standards. 26 September 1980. FIPS PUB 78.
  • (PDF). (PDF) from the original on 23 March 2019.
  • . American National Standards Institute. 9 January 1979. FIPS PUB 71-1980.
  • This article incorporates public domain material from . General Services Administration. Archived from on 2022-01-22.