11.11.2021 | Technical topic

Race of the buses

Race of the buses

nd who says that nothing is happening with the good old bus systems - my ass! If you take the robust CAN bus with its maximum 8 bytes of data, then this has already been upgraded to 64 bytes via CAN FD. Its transmission speed for user data has also been significantly increased, so that the capacity of the bus can be better utilized. And it goes on. The CAN people are already working on CAN XL. The CAN bus should then be able to transport up to 2048 data bytes and reach speeds of up to 10Mbit/s.

But why go to all that trouble, some people ask. Ethernet is already available, and 10, 100 and even 1000 Mbit/s can be transmitted over two-wire lines. Single Pair Ethernet (SPE) is the name of this economical new Ethernet technology.

The ASi bus is now also available in its fifth version. The bus has proven itself above all for networking sensors, actuators and drives and is very popular, for example, in conveyor and storage technology. The new ASi can now transmit up to 32 bytes cyclically instead of 4 bits. The cycle time has also been reduced to 1.2ms. At the same time, the system is backward compatible with earlier versions. Here, too, one can ask why one should not go straight for one of the new Ethernet systems.

The reasons to further develop fieldbuses are the already installed applications, the widely available know-how and also the costs. In the automotive sector, several billion nodes are running with CAN. The new CAN variants offer more performance based on the same technology and communication methods.

If everything in the vehicle were to be completely converted to Ethernet, it would also be necessary to dig deeper into the architecture of the networked devices and processes. The backwards compatibility of the new fieldbus variants ensures that a changeover can also be made step by step with less risk and less effort and that it is not necessary to tighten all the screws at the same time.

So we will continue to get to know a lot of new technology and enhancements to old familiar systems. As we all know, there's life in the old dog yet.



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