CAN Bus has been widely used in mobile machinery for decades because of its reliability, real-time performance, and resistance to harsh operating environments.
Construction equipment, agricultural machinery, mining vehicles, and other off-highway machines rely on CAN networks to connect:
Engine ECUs
Sensors
Hydraulic systems
However, as machines become more intelligent and generate more data, traditional CAN networks can face bandwidth limitations. This is where CAN FD (CAN with Flexible Data-Rate) becomes important.
CAN FD keeps the basic advantages of Classical CAN while allowing larger data payloads and higher data rates during part of the message transmission.
This article explains the differences between CAN FD and Classical CAN and when OEM manufacturers should consider CAN FD for mobile machinery.
Classical CAN is the traditional CAN protocol widely used in automotive and mobile machinery applications.
A standard CAN frame can carry up to:
8 bytes of payload data
This has been sufficient for many machine functions, including:
Engine data
Hydraulic commands
Sensor information
Diagnostic messages
Operator controls
For example:
Engine ECU
↓
Classical CAN
↓
Mobile Controller
↓
HMI / Hydraulic System
For many mobile machines, Classical CAN remains a practical and reliable solution.
CAN FD is an extension of Classical CAN.
Its main advantages include:
Larger data payload
Higher data rate during the data phase
More efficient transmission of larger amounts of information
A CAN FD frame can carry up to:
64 bytes of payload data
Compared with Classical CAN:
Classical CAN
Maximum Payload: 8 Bytes
CAN FD
Maximum Payload: 64 Bytes
This means CAN FD can transmit more information in a single frame.
For machines with increasing numbers of sensors, intelligent devices, and diagnostic functions, this can provide more communication capacity.
| Feature | Classical CAN | CAN FD |
|---|---|---|
| Maximum payload | 8 bytes | 64 bytes |
| Data rate | Fixed | Higher during data phase |
| Network complexity | Lower | Higher |
| Installed base | Very large | Growing |
| Typical use | Traditional machine control | Higher-data applications |
| Compatibility considerations | Mature ecosystem | Requires CAN FD-capable devices |
The most important difference is not simply “CAN FD is faster.”
It provides more flexibility for systems that need to move larger amounts of data efficiently.
Mobile machinery is becoming more electronically complex.
Modern machines may include:
More sensors
Multiple controllers
Electric powertrain systems
Advanced diagnostics
Intelligent attachments
Higher-resolution data
Automated functions
All of these increase communication demand.
Consider a machine with:
Engine ECU
Battery System
Motor Controller
Remote I/O
HMI
Smart Sensors
Machine Controller
If all of these systems generate frequent CAN messages, the available bandwidth of a Classical CAN network may become limited.
CAN FD can help increase communication capacity without immediately moving the entire machine architecture to Ethernet.
With Classical CAN, larger data sets must be divided into multiple messages because each frame can carry only 8 bytes.
CAN FD allows up to 64 bytes in one frame.
For example:
Large Data Set
↓
Classical CAN
↓
Multiple Frames
Compared with:
Large Data Set
↓
CAN FD
↓
Fewer Frames
This can reduce protocol overhead and make data transmission more efficient.
However, the actual benefit depends on message structure and application design.
CAN FD also allows a higher bit rate during the data portion of the frame.
This helps reduce the time required to transmit larger messages.
The arbitration portion of the message still maintains CAN's priority-based access mechanism, while the data phase can operate at a higher rate.
This makes CAN FD useful when engineers want to preserve CAN-style communication while increasing bandwidth.
CAN FD can be useful in several types of applications.
Electric machines often require communication between:
Battery management systems
Inverters
Motor controllers
Main machine controllers
Thermal management systems
These systems can generate more data than traditional hydraulic or diesel machines.
CAN FD can provide additional bandwidth for these networks.
Modern machines increasingly use intelligent sensors that provide more information than simple analog devices.
Examples may include:
Smart position sensors
Advanced pressure sensors
IMUs
Multi-parameter sensors
CAN FD allows larger sensor data sets to be transmitted more efficiently.
Modern OEMs increasingly want access to detailed machine information for:
Diagnostics
Remote service
Data logging
Predictive maintenance
Larger CAN FD frames can make it easier to transfer diagnostic and status information between devices.
Not necessarily.
Classical CAN remains highly suitable for many mobile machinery applications.
For example:
Simple hydraulic control
Basic sensor networks
J1939 engine communication
Remote I/O
Operator controls
If the network has sufficient bandwidth and performs reliably, there may be no reason to replace it.
CAN FD becomes more valuable when:
Bus load becomes high
More devices are added
Larger messages are required
Faster data transfer is needed
Future expansion is expected
The right choice depends on the machine architecture.
Many mobile machines already use J1939 and CANopen.
OEM manufacturers should not assume that existing Classical CAN devices can simply operate on a CAN FD network without checking compatibility.
Important considerations include:
Device hardware support
Protocol support
Network configuration
Bit-rate settings
Gateway requirements
In many machines, Classical CAN and CAN FD may coexist on separate networks.
For example:
CAN 1
J1939 / Classical CAN
↓
Engine ECU
CAN 2
CANopen / Classical CAN
↓
Remote I/O
CAN 3
CAN FD
↓
Advanced Devices
A multi-CAN controller can connect these different subsystems.
CAN FD should also not be viewed as a replacement for Ethernet.
Each technology serves different requirements.
A future machine may use:
Sensors / Actuators
↓
Classical CAN
↓
Local Controllers
↓
CAN FD
↓
Main Controller
↓
Ethernet
↓
HMI / Gateway / Connectivity
Classical CAN can continue handling simple real-time control.
CAN FD can provide additional bandwidth between intelligent devices.
Ethernet can support high-bandwidth applications such as cameras, large data transfer, and advanced connectivity.
This creates a hybrid communication architecture.
CAN FD may be worth considering when:
The Classical CAN network is approaching its bandwidth limits
The machine contains many intelligent devices
More diagnostic data needs to be transmitted
Electric powertrain systems generate higher data demand
Future software functions require additional communication capacity
A new machine platform is being designed for long-term expansion
However, engineers should also consider:
Component availability
Existing device compatibility
Development complexity
Network requirements
Cost
CAN FD should solve a real communication problem rather than being added only because it is newer.
Classical CAN remains one of the most important communication technologies in mobile machinery, but modern machines are demanding more bandwidth and more flexible data exchange.
CAN FD extends the CAN architecture by increasing payload size from 8 bytes to 64 bytes and allowing higher data rates during the data phase.
For OEM manufacturers developing electric, intelligent, or increasingly connected mobile machines, CAN FD can provide additional communication capacity while retaining many of the advantages of traditional CAN.
The future of mobile machinery communication is unlikely to rely on only one network technology. Instead, Classical CAN, CAN FD, and Ethernet can work together as part of a layered electronic architecture.
SonnePower provides programmable mobile controllers, HMI displays, remote I/O modules, and customized electronic control solutions for mobile machinery.
With support for multiple CAN interfaces and flexible communication architectures, SonnePower helps OEM manufacturers integrate controllers, sensors, engine systems, I/O devices, and other electronic subsystems into reliable mobile machine control platforms.
English
