Advanced Data Communication Control Procedures

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In telecommunication, 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.[1]

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.[2]

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,[3] ADCCP specifies a 2-byte control field format with the P/F flag duplicated.[4] 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 byte Second byte Description
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
0 N(S) P/F N(R) I frame, N(S) is a 3-bit send sequence number
1 0 type P/F N(R) S frame, N(R) is a 3-bit receive sequence number
1 1 type P/F type U frame
0 N(S) P/F N(R) Extended I frame, N(S) is a 7-bit sequence number
1 0 type —0— P/F N(R) Extended S frame, N(R) is a 7-bit sequence number
1 1 type P/F type P/F —0— Extended U frame (ADCCP only)

See also[edit]


  1. ^ Friend et al. 1988, p. 191
  2. ^ NBS 1980, p. 6, §3.0 ADCCP classes of procedures
  3. ^ ISO 1984, p. 18, §7.4 Extended control field formats
  4. ^ ANSI 1979, p. 28, §5.2.2 Extended control field
  • 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.CS1 maint: ref=harv (link)
  • Guideline for implementing advanced data communication control procedures (ADCCP). National Bureau of Standards. 26 September 1980. FIPS PUB 78.
  • ISO 4335:1984 Data Communication—High Level Data Link Control Procedures—Consolidation of Elements of Procedures (PDF). Archived (PDF) from the original on 23 March 2019. Alt URL
  • ANSI X3.66-1979: American National Standard for advanced data communication procedures (ADCCP). American National Standards Institute. 9 January 1979. FIPS PUB 71-1980.
  •  This article incorporates public domain material from the General Services Administration document: "Federal Standard 1037C".