ANSI X3.28
Developed by the Allen-Bradley company for communication between control stations and substations, ANSI X3.28 (or "Data Highway" and "Data Highway Plus" as it is sometimes called) was also used by ABB for communication between their SCS-100 telecontrol system and SPIDER MicroSCADA. As might be gathered from its name, it is based on the ANSI X3.28 standard.
DF1 is a successor protocol and an expansion to the ANSI X3.28.
ISO/OSI Model
| 7 | Application Layer | Data Highway Application Layer |
| 6 | Presentation Layer | n/a |
| 5 | Session Layer | n/a |
| 4 | Transport Layer | n/a |
| 3 | Network Layer | n/a |
| 2 | Link Layer | ANSI X3.28 |
| 1 | Physical Layer | RS232 (V.24), RS485 |
