Comparison
ASG vs CAN / CAN-FD
CAN is the arbitration-based, event-triggered serial bus at the centre of almost every vehicle built today; ASG replaces both the arbitration and the harness it needs with one synchronous ring.
StandardISO 11898. CAN-FD adds a faster data phase (ISO 11898-1:2015).
CAN has earned its place. It is simple, cheap to implement, extraordinarily well understood, and it fails gracefully. Most objections to CAN are really objections to what happens when a whole vehicle is built from many CAN buses joined by gateways.
So the comparison that matters is not CAN against ASG frame for frame. It is a fleet of event-triggered buses, each with its own timing to validate, against one architecture where the timing is fixed and the state is shared.
At a glance
A robust multi-drop bus. Nodes contend for the wire by identifier priority, and a frame is sent when a node has something to say. Control logic lives in the ECUs bolted onto it.
A control architecture. Every node joins one ring, and the whole electrical state of the vehicle is committed together every millisecond. There is no bus to contend for.
Topology
How they differ
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Media access
CAN / CAN-FDNodes arbitrate for the bus bit by bit; the highest-priority identifier wins and lower-priority frames wait.
ASGEach zone transmits on its own carrier. Nothing waits for the channel.
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Latency under load
CAN / CAN-FDA low-priority frame’s delay depends on everything else queued at that moment. Worst-case analysis is possible, but it must be redone whenever traffic changes.
ASGEvery event is committed on the next 1 ms tick, at any bus load, with no reanalysis.
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Topology and wiring
CAN / CAN-FDA dedicated pair per bus, terminated at both ends, plus separate power. A real vehicle runs several CAN buses and the gateways between them.
ASGOne ring carries power and data. Zones attach to the nearest module within a wire-length budget.
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Vehicle state
CAN / CAN-FDNo node holds a full picture; vehicle state is reconstructed in software from the frames each ECU happens to subscribe to.
ASGEvery module holds the whole committed state vector each millisecond.
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Adding a function
CAN / CAN-FDNew signals mean new message definitions, sometimes a new bus or gateway, and a fresh timing validation across the affected buses.
ASGDeclare the node and write the function against the state that is already there.
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Fault protection
CAN / CAN-FDError frames and bus-off recovery handle protocol faults; a shorted or babbling node can still disturb the whole bus.
ASGEach block reacts locally in about 10 microseconds, acting as an electronic fuse, so no relays are needed.
Common ground
The matrix
| Dimension | CAN / CAN-FD | ASG |
|---|---|---|
| What it is | A communication bus. Control logic sits in the ECUs on top of it. | A control architecture: protocol, real-time OS and ring channel as one system. |
| Topology | Linear multi-drop bus with short stubs and a termination resistor at each end. | Single ring routed through the vehicle volume; zones attach within a wire-length budget. |
| Medium | Dedicated differential twisted pair. Power is routed separately. | Power and data on the same conductors (PLC over 12 / 24 / 48 V), or a twisted pair. |
| Media access | Non-destructive bit arbitration by identifier priority (CSMA/CR). | Frequency-division. Each zone has its own carrier (a diad); no contention for the channel. |
| Timing model | Event-triggered. A frame is sent when a node has something to send. | One global commit every 1 ms. Every zone updates in the same instant. |
| Determinism under load | Priority-dependent. Low-priority frames are delayed as bus load rises; jitter grows. | Fixed. Every event lands on the 1 ms grid regardless of how many zones or events. |
| Raw data rate † | 1 Mbit/s classical; up to 5-8 Mbit/s for the CAN-FD data phase. | ~2.7 Mbps on the shared channel; capacity added by carriers, not by frame time. |
| Vehicle-wide state | None. Each node knows only the frames it subscribes to; a full picture is assembled in software. | Native. Every module holds the whole committed state vector each millisecond. |
| Compute model | Sequential. Each ECU runs its own loop against its own inbox. | Distributed and time-parallel: every module computes on the same state in the same window. |
| Harness impact † | A dedicated pair per bus, plus separate power. Several buses and gateways per vehicle. | One ring carrying power and data. ~200-300 m of wiring per vehicle in ASG's own figures. |
| Fault handling | Error frames and bus-off recovery; a shorted or babbling node can take a bus down. | 10 us local reaction in each block acts as an electronic fuse; no relays needed. |
| Standardisation & maturity | ISO 11898. Decades of field history; the default in-vehicle bus. | ISO-compliant seven-layer protocol; pre-series. Standard number and assessments still to be cited. |
| Tooling & ecosystem | Vast. Every vendor, analyser and test suite supports it. | Early. A public simulator; silicon, stacks and test tools are in development. |
† derivation still to be confirmed. Legacy figures are the nominal values from the published standards; ASG figures are set out on the methodology page.
Where CAN / CAN-FD is the better choice today
- Ubiquity and cost
Every microcontroller family, every supplier and every workshop already speaks CAN. Transceivers cost cents. For a single low-rate function, nothing is cheaper to add.
- Field history
Three decades of production use. The failure modes, the analysis methods and the tools are thoroughly understood.
- Graceful part fitment
A CAN node can be added or removed with no central schedule to regenerate. ASG re-derives its zone plan instead, which is a design-time step.
- Standard maturity
ISO 11898 is stable and universally implemented. ASG’s protocol is ISO-structured but pre-series, and the specific standard reference is still to be cited.
Questions
Is ASG faster than CAN?
For a single message on a quiet bus, raw latency is similar, and CAN-FD can move a large payload faster. ASG’s advantage is that the 1 ms figure never changes with load or vehicle size, so there is nothing to re-validate.
Can ASG and CAN coexist during a transition?
Yes. The zone module speaks CAN itself: it reads the frame, folds the value into the shared vehicle state on the 1 ms commit, and answers back in CAN to the sub-systems still on the bus. That translation is built into the module, so no separate gateway is added, and it is how a domain-by-domain adoption works.
Does ASG still need CAN-FD for high-rate data?
ASG carries control traffic. Bulk data such as camera video still uses a high-bandwidth link; ASG replaces the control buses, not the video backbone.
What about CAN’s tool ecosystem?
That is a real advantage for CAN today. ASG ships a public simulator and its silicon and stacks are in development; the ecosystem is early by comparison.