@droftarts Thank you for the information. And yes, I have seen all the information above. Most I have not tried, but have read them. I wanted to get the boards correct setup and talking so that do not run into more issue like this down the line. I am new to hardware config and did have the the 6HC wired long ago for motors, hotend, fans and inductive probe. But, once adding CAN things became a bit unclear how to connect things. The above diagrams are nice, but, unclear. Which pinout are you connecting too? I am going from tool 0 on the TDB using CAN 3)CAN1_L and CAN 4) CAN1_H, connecting to CAN-FD 1,2,3,4 ? and going from 1LC to the SZP 1,2,3,4? from where to where on the SZP CAN 1,2,3,4? Is this all using one set TDB CAN wire or two? Am I having to rewire one of the connections? If so, which and how. example?

6HC
1)nc
2)CAN0_H
3)CAN1_H
4)CAN1__L
5)CAN0_L
6)nc

TDB
Tool0
1)CAN_L_0-1
2)CAN_H-0-1
3)CAN1_L
4)CAN1_H

1LC
CAN-FD
1)CAN_L
2)CAN_H
3)CAN_L
4)CAN_H

SZP
Ground
+5v
C_L
C_H

I know that all of this seems very rudimentary for you as if everyone should understand. But, it is not straight forward. I am not trying to be difficult I just want to understand how things should be connected without magic blue smoke. For example.

https://docs.duet3d.com/User_manual/Connecting_hardware/Z_probe_connecting

The example given for the BL touch, should be about the SZP and not the touch. That would be much more helpful AND promote Duet products as an all in one solution. Instead I know more about the BL touch then the SZP. Making better sub categories with short and concise "how to" for Duet 3 6HC and SZP. then another for Duet 3 6HC +1LC + SZP. Then another for Duet 3 6HC + TDB + 1LC+ SZP. Then do the same for the other Duet mainboards. It would cut down on questions in the forums and the very toxic people. K.I.S.S is the goal... then people would be drawn to Duet and not BTT and others. Less chance for blue smoke and better chance of positive paying customers. The very few video out on the Duet and more on CNC then printers... and to be honest they are not that helpful in most cases. So, I just want to stay again... I am not trying to be rude or difficult. But, we go from the duet 3 family intro... to deep in the weeds for so many things that are not Duet. configure a secondary z-probe, but we have not even started on setting up our first.

Maybe another way to look at things...
If I want to confiugure 6HC, what commands are needed to be entered into the config.g for it to work as a printer.

what commands for the: LC1
what commands for the : SZP
what commands for the : MFM

I like the RRF tool. is gets you started. But, then what. how do you know where to go from there? How do I know what commands are needed if any at all? So, should everything work after the RRF? Do you see where the next steps are not so easy to figure out?

well, either way. I have just DE soldered the jumper, refit the two jumpers back on CAN 0 and the TDB jumper is still connected. I am using SBC now. I did in the start. But, removed it all and started troubleshooting. then I added SBC back into the mix once things were talking. I'll go back and reread everything you posted and see if I can figure out the wiring above.

Thank you for your help.