ISO 11783-1 — general and device classes

Part 1 is the table of contents for the whole family: it lays out the layered architecture, defines the roles a participant can play, and — most importantly for day-to-day code — establishes the NAME, the 64-bit identity every control function carries. Everything else in this section is a specialization of the picture Part 1 paints.

Why this exists

ISOBUS is a system standard, not a single protocol. Part 1 exists so that the dozen later parts agree on the same vocabulary: what a “control function” is, what a “device class” means, how identity is structured, and how the layers stack. Without that shared frame, the VT part and the TC part would describe incompatible worlds.

The layered picture

   application services      VT · TC · FS · SC · diagnostics · implement · GNSS
        ───────────────────────────────────────────────────────────────
   identity & messaging      NAME · address claim · requests · transport
        ───────────────────────────────────────────────────────────────
   naming                    PGN · source · destination · priority   (J1939)
        ───────────────────────────────────────────────────────────────
   wire                      250 kbit/s CAN                          (Part 2)

Part 1 owns the top-to-bottom shape; the other parts fill in each band.

Roles and device classes

A participant is a control function (CF) — one job, one identity. A physical box (an ECU) may host several CFs. Part 1’s device-class vocabulary lets a CF say, in its NAME, roughly what kind of machine part it is (a tractor ECU, a planter, a fertilizer system, a positioning device, …). Other nodes use that to decide whether they want to talk to it.

   ECU "ACME-Box"
     ├─ CF: Tractor ECU      (device class = tractor, function = TECU)
     └─ CF: Navigation       (device class = positioning)

machbus models roles in net (the NAME and its fields) and surfaces the role/ownership mapping in Role boundaries.

The NAME, field by field

The NAME answers “what is this?”, not “where is it?”. It is 64 bits, and every field is exposed on net::Name:

   NAME (64 bits) — what a control function IS:

   ┌──────┬──────────┬──────────────┬──────────┬──────────┬──────────┬──────────────┐
   │ self │ industry │ device class │ function │ function │ ECU      │ manufacturer │
   │ cfg  │ group    │ (+ instance) │ code     │ instance │ instance │ + identity # │
   └──────┴──────────┴──────────────┴──────────┴──────────┴──────────┴──────────────┘

   self-cfg = "if I lose my address, I may pick another"
   manufacturer + identity number make every NAME globally unique

Two properties make the NAME the keystone of the whole network:

1. Globally unique — manufacturer code plus identity number guarantee no two CFs share a NAME.
2. Totally ordered — the 64-bit value is directly comparable, so any two CFs can deterministically decide who outranks whom.

Address claiming (Part 5) needs exactly those two properties and nothing more. The self-configurable bit decides a CF’s fate in a conflict: a self-configurable CF that loses its preferred address may take another; one that is not must go silent.

From concept to code

See also

• ISO 11783-5 — address claiming — where the NAME earns its keep.
• The standards, end to end — the whole-system story.