SD (Customer) asked a question.
I have come across several devices that run on CanBus that would clean up a lot of wiring and such compared to what I am doing now. But it doesn't seem to be very accepted in the PLC world. Any ideas why?
I am new to CanBus, so what am I missing? Is it worth my time to review these products and come up with a translation (Canbus->modbusTCP) device that I am happy with?
Hi @SD (Customer)
I am not an expert on CANBUS, but in general, the trend has been to move away from Bus systems and more to Ethernet-based.
"Bus topologies are prone to failure since any cable failure will result in the network not working. Further, as the number of nodes grows, the bus network is subject to substantial performance degradation."
Regards,
Garry
CANbus is primarily seen in the automotive sector with some implementation in building control systems. At this point there will be no widespread adoption of CANbus into industrial automation. Legacy serial networks are being replaced with ethernet topologies and protocols like MQTT and EtherCAT devices will continue to become more popular. CANbus was probably not widely adopted because Rockwell didn't use it. It's probably more advisable to invest in hardware that natively supports common industrial ethernet protocols than writing a translator for CANbus.
CANbus (as used in automotive) is slow and has a number of limitations.
The automotive sector is moving away from it towards a high speed single pair ethernet system. Currently they get around the limits by running multiple busses.
Each industry has their desired protocols. If you're in Mobile equipment you'll spend a lot of time with J1939 over CAN. New industrial networks are almost entirely ethernet based (Modbus TCP, EtherCAT, Profinet, E/IP, etc.). There will lilely never be one standard protocol across all industries as each industry has their own unique use cases.
PLCs with native J1939 support exist for mobile applications, most of these use a Codesys environment.
Rockwell had a CANbus network, called DeviceNet. I used it a lot 10 to 20 years ago, but now, most devices are transitioning to EtherNet/IP
The other option besides EtherNet/IP is EtherCAT. Unfortunately Automation Direct doesn't have any EtherCAT products. AD seems to be pushing only EtherNet/IP like Rockwell is.
EtherCAT is faster, deterministic, intended to support multi-axis synchronized moves, and more reliable. Though it does require special hardware and isnt meant to run on a standard LAN network and is more expensive. Cycle times for EtherCAT communication are usually a quarter millisecond or less and have almost no jitter.
EtherNet/IP is easier to deploy due to using standard network equipment, compatible with more products these days, and easier for many to understand because it runs more like modbus. Typical cycle times for EtherNet/IP are around 10 milliseconds.
CANbus is primarily seen in the automotive sector with some implementation in building control systems. At this point there will be no widespread adoption of CANbus into industrial automation. Legacy serial networks are being replaced with ethernet topologies and protocols like MQTT and EtherCAT devices will continue to become more popular. CANbus was probably not widely adopted because Rockwell didn't use it. It's probably more advisable to invest in hardware that natively supports common industrial ethernet protocols than writing a translator for CANbus.