CAN wiring when swapping out Toolboards

[warpster]

I'm changing my printer over to a toolchanger and all of my tools will be controlled with toolboard 1LCs. I have a tool distribution board that will be the hub for the toolboards. I want the individual tools when sitting in their storage positions to be connected to one of the tool distribution board connectors along with one distribution board connector going to the pickup head.

Say I have 3 tools then I would use 3 of the 4 connectors on the tool distribution board for the 3 tools and the forth connector would be for the tool pickup head which would not have a tool connected unless a particular tool was selected during printing.

What I am thinking is that I would remove all of the jumpers on the tool distribution board and move the jumpers to the tool connectors for each tool. So without any tools loaded the tool distribution jumpers would be removed and jumpers enabled at each tool and the tool would be connected.

The pickup head would also have the jumpers installed at the pickup end thus extending the bus back to the distribution board and eventually to the terminator.

When the pickup head picks up a tool the tool would be disconnected from it's original tool distribution board connector and connected to the connection that goes to the pickup head. In this case the jumpers at the old connector would extend the bus while the tool was loaded.

Is my thinking here correct or am I missing something? Thanks

[warpster]

So no one? I can't find thisin the docs so where do I go to ask if not here?

[A Former User]

This post is deleted!

[dc42]

@warpster when the distance between the tool board and the tool distribution board is very short, you can get away with leaving the jumpers in place on the distribution board and using a 2-wire CAN connection between it and the tool board. So I suggest you use that approach for tools that are docked.

Note, the tool boards draw a surge of current when they are connected to VIN. So if you will be connecting and disconnecting VIN when swapping tools, you should make provision to limit that current surge.

[rjenkinsgb]

I have a junction box on the back of the machine with the tool distribution board and D15 sockets for the tool cables. That allows me to remove tools and just use a dummy plug to link through the CAN bus at any unused connector.

I also have the cables to each fitted tool permanently plugged in!

Although you may get it to work with boards being connected and disconnected, I suspect there will be CAN errors and require continuous resets as boards appear and disappear from the bus, as seen by the controller.

I've just copied the E3D cable support setup, which uses long springy steel cable ties to keep the tool cables formed in to upright loops.

More photos here:
https://forum.duet3d.com/topic/25709/meet-the-frankentron

Video here:
https://www.youtube.com/watch?v=x-ut81sn-io

[warpster]

@dc42 Thanks, there should be an overlap where, during switching, the power will be applied from both sides so it should not ever drop power. You say "very short", does ~18" qualify? So then leave tool distribution jumpers in place for the docked tools but for the pickup head jumper it at the head and leave the jumpers off on the distribution board for just that connector since it will have ~50" of wiring?

[dc42]

@warpster why do you need 18" of cable between the distribution board and each of the tool docks? Assuming the tool docks are arranged in a row, can't you put the distribution board just below the centre of that row?

Alternatively, don't use the distribution board for the CAN wiring. Instead run the CAN cable from the main board to the first dock, then on to the second dock, and so on.

[warpster]

@dc42 I'm just saying with where the distribution board is located now the cables would be around 18". Yes it could be moved but would I rather not. Thanks