Inductive Limit Switch problem

[JAZZCNC]

Throw it in the bin I say..

[Kitwn]

Throw it in the bin I say..

I promise I will do exactly that. As soon as I receive your cheque for the $400 AUD or so that I'll need to replace it with something better. Now THAT'S how you give a Yorkshireman a heart attack

[JAZZCNC]

I promise I will do exactly that. As soon as I receive your cheque for the $400 AUD or so that I'll need to replace it with something better. Now THAT'S how you give a Yorkshireman a heart attack

If you are prepared to use Mach3/4 then I've probably got something I could send your way.

[Kitwn]

If you are prepared to use Mach3/4 then I've probably got something I could send your way.

PM sent.

[Kitwn]

I'll stick with my self-centred view of having BoBs and similar with opto-isolated inputs. I've never been a fan of distributing a high speed logic input signal into the big, bad world.

I'm in complete agreement with you on that one, but the logic following it probably needs to be slightly different from the input circuit to my cheapo card. Something with a supply voltage well above 5V would be a good start.

EDIT: Been doing a bit more looking at opto-couplers and there certainly is a big range of options. The Darlington output types have a higher saturated output (up to 1V) compared to the conventional type (as low as 0.1 - 0.2V at low current) so you really must choose your device, but there are devices that would interface successfully to the cheap card. Since this application is at a guaranteed very low frequency I'm happy to let old technology do the job this time.

[Kitwn]

Just been perusing the HDBB2 breakout board from CNC Drive. This appears to be nothing more than an up-market version of the cheap Chinese parallel port breakout board with opto-coupled inputs and a number of improved features. The company advertise this board as suitable for use with LinuxCNC direct from an old PC's parallel port as well as with CNC Drive's own products. Since this board is a necessary add-on to the UC400ETH Ethernet controller anyway, it might make a good starting buy for a budget build with the option to upgrade at a later date.
Has anybody used one of these in this way?

https://www.benl.ebay.be/itm/HDBB2-b...-/121287188690

[Doddy]

That UCSB board, on paper, looks to be a pretty good BoB for the extra ports on (at least) the UC300ETH. It's pricey, though, but looks to be built like the proverbial brick-outhouse. Probably a bit of an overkill for most machines (how many layers of optical isolation do you really need?) but if you're happy with the price. I'd be thinking that if I was ever to need more than the 12 outputs (bearing in mind you'll need 8-9 for a 4-axis) then I'd relegate the axis stepper signals to a cheaper BoB on the port 2/3 on the 300 and retain the highly flexible I/O of the UCSB for other purposes on the machine.

[Kitwn]

At last!! A nice man in a white van turned up today with a box from RS containing the cable for re-wiring my new proximity sensors. I managed to get the old wiring ripped out of the drag chains and the new cables in place for the Y and Z sensors before wine 'o' clock.

Tomorrow I should have time to get the two X axis sensors wiring in place and all the soldering done to connect everything up to the control box. Sadly the two remaining miniature relays for coupling the sensors into the BOB are a separate order which is still on it's way from somewhere on planet Earth, but I should be able to test all the wiring and confirm that everything else works as expected. I already have a list of outstanding projects from Mrs W-N that are waiting for the machine to be back in action so I'm hoping the relays arrive soon!

[Kitwn]

I was just getting to the end of all the new wiring when the same nice man in the same white van turned up with another parcel from RS containing the relays. Apart from a slight problem mentioned elsewhere I now have the 4 new proximity sensors wired up with screened cables back to the controller and the relay/transistor interface into the BOB finished and tested.
Tomorrow I will tidy up the impressive mess and get everything put back together and ready for testing and alignment. Auto-squaring will need to be re-calibrated and the finished aluminium (rather than the old plywood prototype) Z axis lined up as well. Might be able to make something soon!

[cropwell]

Kit,

If you find reed relays in the homing circuit don't give you a consistent zero point, you could try DC-DC SSR's