I have recently made two very similar CAN Boards, so it is a bit interesting to look at the differences since they have the same basic design.
This first one is a M12 design (Above) – the name after the M12 connectors at right. It’s main purpose is to fit into a waterproof module with 8+2 expansion boards based on very fast TTL serial links. The first layout of these boards are working, but I put futher design a bit on ice due to other work. The SWD used was complicated to us, USB a complete disaster and the footprint on the CAN Tranceiver was wrong. But, this design will be continued and upgraded.
The next one was finished a few secs ago and contain several changes from the M12 version. Firstly it target a standard metal box (not waterproof) and add Ethernet, SD-Card, proper USB and an isolated 24V Power Supplly. DC/DC on CAN ports are also swapped out. I kept SPI Flash, but added PSRAM option. It is an option to modify footprints so a SPI FRAM will fit because they are a bit more narrow. You can alsp see that CAN Tranceivers are corrected and that SWD is replaced with the old one I have used for years. The number of modules are reduced to four because you only talk about some extra modules in the same box.
This last board use ribbon connectors at right that will be 1:1 to DSUB9 ribbon connectors. The box will fit 6 DSub-9 at right so to get from 3 to 6 we just add another board in the box and use the later board as an extension board (dropping components we don’t need) – we can then chose to add 3 x CAN, 3 x Serial or GPIO. This board took ages to get right, but it only took me a few hours this morning to actually routing it.
The black frame around the picture is because this was exported directly from KiCAD. Usually I prepare pictures using 3D paint, but I wanted to see how it was to export one directly.
It has been a cock-up with packages out of China – the sellers send my packages out and get them returned from the Airport. Not sure why, but Norway have an automated VAT system where they are mental on collecting VAT on everything – the system works well, but my wife adviced me to put the VAT number from AliExpress in the address – that seems to work better. As a consequence I have not recevied the metal boxes yet.
Needless to say I can scale up systems using the Ethernet as backbone. I used ca 3 days to manually add lwIP TC/IP stack and I have C code for a Profinet stack so fun will happen.