Hi,

Of course, you are correct that the system has no way of knowing which limit has been hit.

Its worse, Mach thinks that all nine switches have been hit at once....and that explains the great big long Log entries about all the switches being activated.

I wasn't the one who set it up originally, but to be fair it has worked fine this way with Mach3.

And you could, at a pinch get the same working in Mach4.....but that's like saying 'my old Model T had trembler coil ignition, so it should work for a 2023 model car as well'

Craig

lol!  Well it sounds like I need to take it apart and do some rewiring.

Hi,

I have three Home switches, one for each axis, each on their own ESS input. I have 6 Limit switches, two per axis for all three axes, there again each on their own input,
for a total of nine inputs. Then Mach knows exactly which switch operated and what that portends.

I hasten to point out that I have been described as 'anal retentive over this matter'....which I think is rather unfair....I just like hopping up and down on the spot a lot!
I'm not drunk, I'm just holding up this lampost if you really want to know' (not original but a misquote of Tom Waits)

Craig

It makes sense, I just never thought about it since that's the way the machine came wired. Thanks again for the input and taking the time to reply. 

Hi,
are you familiar with the placement of the switches inside the machine?

It was very common and still is, to have two limit switches per axis, naturally enough one at each end of the axis, and to use one of those switches as a Home switch
when homing but otherwise as a limit switch. This is perfectly acceptable even if it does not really go 'whole hog' such as I described on my machine.

I do reiterate the point that the most valuable use of switch is not  Limits, but rather Home switches. If you religiously Home your machine at startup and enable SoftLimits
then your machine will never cross over the boundary of your machine, ie the Limit switches will never be triggered.

My first mini-mill was like that, I had three Home switches only and thereafter relied on SoftLimits. It worked extremely well. I had three crashes in seven years and in every
instance it was my own fault. I always meant to get around to fitting Limit switches but never did. My new build mill is much bigger ans very much faster, 25m/min rapids,
and so I determined that I needed not only SoftLimits but Limit switches as well.

The reason I mention this is because Home switch can be anywhere in the machines envelope. Limits switches all but have to be at the extreme of travel, but not so Home switches.
Having said that its common to fit them near to one end of an axis, but not strictly required. For example my Home switches are about 10mm 'inside' the boundary. When the machine is Homed
the machine coordinate is usually set to zero at the Home switch position, but optionally can be set at a 'Home Offset'. In my case I make the Home Offest 10. So when the machine
is homed to the Home switch Mach knows that the actual boundary is a further 10mm away.

Being able to locate Home switches at any convenient location may often mean an easier placement, out of harms way, out of the coolant stream or whatever. It may also give you the oppurtunity
to design your Home switch installation that they not be damaged by over-run.

I use Omron roller plunger snap action microswitches for both Homes and Limits. They are high quality and have highly repeatable hysteresis, another matter where  I 'hop up and down a bit'.
I Home or Reference my machine (without the complication of Index Homing) within 0.02mm which is entirely adequate for most things.

https://nz.element14.com/omron-industrial-automation/z-15gq22-b/micro-sw-roller-plunger-spdt-15a/dp/1500340

Craig

I have the same problem like You - https://warp9td.com/index.php/kunena/7-general-discussion/9456-ess-homing-setup-failure

Craig, my switches are all proximity sensors... are there advantages to using mechanical switches?

FiveO,

I have the same problem like You - https://warp9td.com/index.php/kunena/7-general-discussion/9456-ess-homing-setup-failure

I'm glad I'm not the only one.  I haven't been able to get on the warptd forums... my registration email never arrived, and the email I sent to support has not yet been answered.  Are there any helpful hints in the thread you listed?

FiveO,

Quote from: FiveO on March 08, 2023, 02:12:20 AM

I have the same problem like You - https://warp9td.com/index.php/kunena/7-general-discussion/9456-ess-homing-setup-failure

I'm glad I'm not the only one.  I haven't been able to get on the warptd forums... my registration email never arrived, and the email I sent to support has not yet been answered.  Are there any helpful hints in the thread you listed?

The forum is helpful there. At now I think Andrew(warp9 forum) is busy with newer version quote:"I have been chasing some other issues at the same time to deal with not only build 5000 issues but other features added since then. I am trying to get one stable build working where everyone just jumps from 4809 to 5070."

So get these versions until then: Mach4 - 4.2.0.4809 and ESS - 278.1 (https://warp9td.com/index.php/gettingstarted/setting-up-the-smoothstepper-and-mach4)

Hi,

Craig, my switches are all proximity sensors... are there advantages to using mechanical switches?

For Home switches I believe there are advantages, for Limits, no.

For a Limit switch all that you really care about is that the switch operates when the axis is adjacent the switch. It does not especially matter if it operates +-0.1mm
nor does it particularly matter when the switch deactivates when you back up.

Home switches are different. Recall that Mach references the machine coordinate of an axis to zero (or Home Offset if so programmed) not when the switch activates but when it deactivates.
The axis will advance towards the Home switch until the switch activates and then decelerate to a stop. Then the axis will back up and the machine coordinate zeroed as the switch deactivates.
There is a premium here on exactly when a switch activates and when it deactivates. Snap action micro switches are very good at repeatably activating at exactly the same spot again and again.
The Omron switches I use have a precisely defined and repeatable hysteresis, ie a given travel before the switch deactivates.

With proximity switches and to a certain extent optical switches there is a minor variation not only when the switch operates but most importantly when the switch decativates when the axis reverses.
Its for this reason that I prefer snap action microswitches for Home switches.

Having told you the reason that I like mechanical switches there will be many to say the contrary and with experience to back the claim. I suspect in truth both solutions are adequate.

If you really want accurate homing then you'd use Index Homing. Given that I have servos on all my axes and the the servo drives have an auxiliary encoder output including an Index signal
I could invoke Index Homing easily. It would require an extra input to Mach for each axis of course, so four currently and five coming.

I made my own breakout board for my new mill. It has an eight wire plug for each of the six axes, four wires for differential Step/Dir signalling, one for an Enable, one for a Reset,
one for a servo Alarm and the last one is a 0V Return. I could I suppose redesign to have say a 10 wire plug which would allow at least one extra wire for Index Homing....but really do I need it?
I can Home or Reference my linear axes to within 0.02mm just with snap action microswitches....is that not good enough? I could with Index Homing do better, to within 1um....but is that
really a big advantage of just skiting? Once I fully develop my fourth and fifth axes I may have to revisit this decision, I really need to Home or Reference my rotary axes within say 15 arc secs,
and I suspect that Index Homing may be the only way to get that sort of accuracy. If that were the case then I would retrofit just the fourth and fifth axis with Index encoders rather than redesign
my breakout board.

Craig