CAN frame size

frame ‘size’ parameter (optional)
When connecting directly to a CAN device with supported CAN Adapters, a CAN frame may contain less than standard 8 bytes. The size parameter can be used to specify a custom number (1-8) of bytes contained by CAN frame:

One can reduce this but what a waste for frame, as there are 8 byte over head.

I really thing will be nice to be able to increase this, as today there is %50 waste, if we can make this up to 16 or 32 bytes or more , then the frame over head will be very small.

it can keep the internal frame order and size the same just auto increment to next frame for bytes after the 8th byte, also may be option check sum at end will be nice to make sure frames with error are not used.

we are almost ready to release our hardware, it would be really nice if you can add this option to version two, leave default to 8, we do not want to increase baud rate due to other reasons, so at 115200, we send some much data and we can send more data each frame it will improve our frame update rate substantially.


We want to keep the protocol compatible with real CAN network, so there is no plans to increase the frame size over 8 bytes.

I remember back in the day when the planet was cooling this came up with ethernet frames and the adoption of jumbo frames, the argument was that once you start extending the frame length of the standard, where do you stop? The overhead reason is still a valid argument.

As it happens, there is a new CAN specification called CAN FD:

CAN FD allows variable payload size up to 64 bytes. That is something I could develop support for if interested.

CAN FD frame support has been added to RealDash CAN protocol. See updated documentation here: