Wacko limit switch behavior: help requested

[DDG2]

In an attempt to dump mechanical limit switches, I installed 3 Hall effect sensors as shown below. When I magnet is passed over the individual sensors its relay indicator lights up and the normally closed relay breaks the circuit to kill the appropriate axis. This works, but...

Each limit switch works so that it stops the travel of that particular axis and requires a reset to continue with its travel.
If you fail to move that axis after resetting it, the other two axes will run passed their stops even though their individual relays are triggered.

This might make it easier to envision what happens:

Scenario 1:

Y hits a limit and stops. I reset it and move it again to make sure it was reset. Then I test X. It hits a stop, I reset it, test to make sure it travels. Ditto for Z.

Scenario 2:

Y hits a limit and stops. I reset it but I DON'T jog it to test for a reset. Then I test X. It passes its magnet, lights up its relay, but continues to travel without setting off an alarm, eventually crashes.

I've tried for a couple of days to figure it out but I'm stumped. Any ideas? I appreciate any help. Diagram attached.

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[CitizenOfDreams]

I can see two possible reasons for this.

1. Your CNC controller (you didn't say which one you have) has a bug that causes this unexpected behavior. Unlikely yet possible.
2. Your limit switch circuitry somehow disables the rest of the limit signals when one of the limit switches is active. Watch your breakout board inputs while running the test to make sure the signals are where they should be.

By the way, what is the purpose of disabling each axis separately? Normally, hitting a hardware limit switch is an emergency situation that should stop the machine completely until the problem is rectified.

[DDG2]

"... controller (you didn't say which one you have) has a bug ..."

No one should leave out critical data if they expect help. And I knew I wasn't giving much info on the controller, etc. "Longs" is really all I know, though I can dig deeper to get more data on them.

"Your limit switch circuitry somehow disables the rest of the limit signals when one of the limit switches is active."

Yep, that was my first thought. But-- the individual relays still activate (indicator lights comes on) as they come to the magnets. Furthermore, the other two stops work as long as I jogged the first axis (any distance) after it gets reset. Crazy!

"... what is the purpose of disabling each axis separately?"

As they are now behaving, an all-go-home command would have one axis going to its magnet and stopping. The other two axes would run past their mags and crash. Since posting my question, I've come to suspect the relays are somehow causing the problem. Maybe if I use sensors that go low when near the mags and just connect the output wires from them to the breakout board. ???

[CitizenOfDreams]

Since posting my question, I've come to suspect the relays are somehow causing the problem. Maybe if I use sensors that go low when near the mags and just connect the output wires from them to the breakout board. ???

If you are using the relays simply for inverting the signals from the Hall sensors, is it possible to reconfigure the controller instead? What does it look like, does it have any setup menus, configuration files, anything like that?

[dazp1976]

If it's a Longs 'kit' it's generally a board like this below.
Do you really need to go through relays just for a few switches and an e stop?

[DDG2]

The pic shown by dazp1976 is my breakout board. The drivers have tiny toggle switches also. Yes, I am using the relays to invert the signals. Probably stupid (ignorant) on my part. I'll post pic of the drivers.

[dazp1976]

I haven't got round to wring mine up yet but:
This is my board:

This is how I was shown to wire an individual switch:

This is how I was shown to wire them in series:

So no relays or anything.

Mine are npn no type. Hopefully they work and sounds like I'm going to have some intresting times when it comes to fitting them!!

[DDG2]

Ok! Thanks to both of you! I think I know what to try. Probably just need to use diagrams from dasp1976 and ditch the relays. That'll be better anyhow, fewer parts. Thanks again guys!

[DDG2]

I'm listening to each of you and using my pea sized brain to interpret what you ask and suggest. Last night I removed the relay pack and wired it up as shown in the attached pic. It was a total fail. When the Hall effect sensors are triggered (or when they're not) the axes jog as if the sensors weren't even there. I didn't use the diodes as suggested by the dazp1976 drawing because I didn't see why they would be needed. Maybe that will be my next effort unless there are other suggestions.

[ZASto]

So, you have a schematic from dazp1976 and connecting switches differently
I answered you on NFS forum.
BTW, you should power your sensors with min. 6V (depends on type) up to 26 or 36V.

[dazp1976]

I'm wondering what type of sensors you have and if the voltage you are feeding them is too low.
Just thought I'd share my experience today.

I wired a couple of mine up for a quick test.
They are inductive NPN NO type. Wired them to my bob using my diagram for the NPN version (no diodes etc).
Now. My board uses 5v power for the outputs and then a seperate 12-24v supply for it's inputs and spindle control. (I'm using a 24v).

So my sensors are powered by the 24v supply through the brown + & blue - wires.
The black wire feeds into the input. Mach needed to be active low.

Moved a metal block up to it, the led lit, mach went into emergency. Nothing would work.
I couldn't reset it until the block was moved. When I got it reset nothing moved unless I told it to.

I'm guessing this is how it should function correctly.
I really should get these finally fitted up I reckon.

[DDG2]

NFS forum? I'm not familiar. Been ill past couple of days. I'll be back at it soon with trials of suggested fixes.

[DDG2]

I've been under the weather passed couple of days. Haven't been able to keep up with all the posts. Please be sure to share your setup with us.

[ZASto]

NFS forum? I'm not familiar. Been ill past couple of days. I'll be back at it soon with trials of suggested fixes.

Mach support forum, owned by New Fangled Solulutions.

Particular topic: https://www.machsupport.com/forum/in...?topic=42936.0
Guess that you started it

[DDG2]

Wired it per the NPN drawing late last night. Going to try it later today.

[DDG2]

Per advice from various respondents, I removed the relays altogether and wired it as they recommended. Pics with values attached. As the magnets passed the sensors, the lights in the sensors came on and the voltage changed from 3.75v to 0.08v but no alarms were triggered, like the sensors weren't even there. As far as I could tell, there was nothing happening on the diagnostics screen with or without the sensor activated. The saga continues.

[DDG2]

Instead of 12v I went ahead and used the 36v from my main power supply. Made the sensor lights much brighter of course. But still no trigger action. So far, the closest I've come to success was the 8 relay block. But it does have that one problem mentioned in my original post. And, of course, the primitive mechanical micro switches that I used for several years worked. But they were so crappy looking. I really would like to get this to work. No moving parts, nice clean look.