[Mzones]

ger21

Unless your board is shorted internally (highly unlikely), imo the "Limit Switch Triggered" message indicates a noise issue

Then I re attached the existing cable to the probe. As soon as I attach the alligator clip to the bit message says either "Estop" or "Limit Triggered" Every time I do this, the message alternates to one or the other.

How about the possibility of a external connection changing the pin state on all outputs at once?
I know it's hard to tell without a complete schematic, and software configuration.

This thread is not finished yet.
What do you think?

[Mzones]

Am I correct here?
You are connecting 5V+ through a 56-1K resistor then connected to the tool bit.
Your plate is connected to pin 13 on the BOB.
when the tool bit makes contact with the plate pin 13 goes high.
I'm having a hard time seeing how this works.

[john-100]

yes

thats what the diagram in post 17 shows and only works when the spindle is insulated
and the jumper set to pull down the input via the 4K7 resistor on the PCB

the added resistor is optional and protects the +5V supply from an accidental short circuit

John

[Mzones]

You are connecting 5V+ through a 56-1K resistor then connected to the tool bit.
Your plate is connected to pin 15 on the BOB.
when the tool bit makes contact with the plate pin 15 goes high.
I'm having a hard time seeing how this works.

You are connecting 5V+ through a 56-1K resistor then connected to the tool bit.
Why are you connecting this 5V+ to ground ? Seems to me that this maybe the reason why
the EStop and limits are tripping. because its pulling all the outputs low on the input header.
I do not believe that this is a noise problem.
The error message about Estop or Limit trip error message shown depends on which Mach recognized first.

I'M assuming that you have 5V+ connected through the Estop switch then to pin 10 on the bob.
I'M assuming that you have 5V+ connected through the limit switches then to pin 13 on the bob.
These connections have no current limiting resistor. Why aren't these getting hot ?
Why Use such high wattage resistors in a TTL level circuit ?

Shouldn't the solution for fixing one problem not create another problem ?

When I identified this problem ( Post # 7 on this thread)
I didn't have to explain my how I would approach solving your problem.

There is more than one way to fix most any problem, it's up to you to decide which approach to take.


Attached is a schematic of what I would do it.

Attachment 218926

[john-100]

Hi mzones

the 1K pull up resistor in post 11 is the simplest solution
that did not require making a PCB and only uses one component
that can be secured by the C10's terminals

in view of the limited range of resistors Nicolas had to hand for the initial tests
and the limited range of resistors available in his local store

I selected the 36 ohm 10W resistor Nicolas had for the initial tests
and in post 19 a range of 1/8 or 1/4 watt resistors to buy to complete the installation

(a 36 ohm 1 Watt resistor across the 5V supply will only take 0.138 A
and should not be a problem either)

the alternative circuit in post 17 has the resistor added to protect the 5V supply
as I expect its more likely to be short circuited by accident
than the positive supply to the E stop or limit switches

without any other details I expect the other issues may be due to the jumper being
in the pull up position at some point since the BOB is now working correctly

John

[kolias]

Hey Mzones why you try to make life more complicated? John provided an excellent simple solution to the problem I had and now all is working fine.

Which problem you identified in post #7? I see nothing there

And what do you mean about "These connections have no current limiting resistor. Why aren't these getting hot?"

All pins 10-13 and 15 are set to pull down

Yes there is more than one way to fix any problem and John choose the simplest including parts I had available. Good show John

[ger21]

Hey Mzones why you try to make life more complicated?

I think he just wants to know why you were getting the results you were getting. Knowledge is never a bad thing.

[Mzones]

Which problem you identified in post #7? I see nothing there

The probe consist of an alligator clip which is connected to the GND and a metal plate which is connected to an input pin on C10

Here at your first post there two different problems.

At this point input pins are set to 0 volts, (jumper set to pull down.)
Pin 15 is connected to the plate. Probe is connected to gnd on the BOB.
When the probe makes contact with the plate this creates continuity between
pin 15 (0 volts) and gnd.

Therefor the circuit you have described here, is switching 0 volts to ground

Switching 0 volts to ground isn't going to do anything.

A problem identified post#7 !

"Limit Switch is Triggered" tells you not that the tool hit the plate, but that a limit switch was triggered. What this means is that you either have the plate wired to a limit switch input, or, noise is triggering your limit switches when the tool touches the plate. The bit doesn't rise 1" because Mach3 is stopping on the limit switch trigger.

With the limit switches in there normal state 5 volts is sent to Pin 11 setting it high.
The way you had it wired at this time. probe contact sends pin 11 low triggering limit switch.
This totally explains this issue.

A problem Identified by ger21

Then I re attached the existing cable to the probe. As soon as I attach the alligator clip to the bit message says either "Estop" or "Limit Triggered" Every time I do this, the message alternates to one or the other.

Attaching the alligator clip to the bit you created a path sending output pins low ,
triggering Estop and limit switches Like maybe you had the alligator clip connected to the
5 volts of the input pin section. this would explain this.

only works when the spindle is insulated

I agree that this will work IF the spindle is isolated.

I'm curious though just how you plan on getting the spindle isolated.
This seems to be another problem created by the approach that you are taking.

The circuit I posted here does not need to be isolated, nor would it
create other problems that you have encountered here.
Just do it as a bug.

Like I said about different people having different solutions for the same problem,
here is another one of my prospectives.


Put simply this could also be done by using pull up jumper setting., Sinking the Estop limit switches
and the probe signals. This would not require any external resistors, as they are already in the BOB

As to making this complicated Maybe l can go into my personal configurations and invert the signal for that pin.

Hey Mzones why you try to make life more complicated?

I'm not your doing a mighty fine job on your owe!

Mike

[truckeic]

Hi Nicolas

Great , just the result we want

its just a matter of having the probe pulling the input in the opposite direction to
the on board pullup / pull down resistor
(not always easy see if you spend too long looking with out a break )


the resistors maximum voltage is not going to be an issue since the circuit only has a 5V supply

using a 1/4 watt resistor any thing from 120 ohms to 1000 ohms will be OK

with 1/8 watt resistors use 270 ohms to 1000 ohm resistors

(the values are high enough not to run the resistors at the maximum wattage
I aim for 70 to 80 % of the maximum )


if your local store is like the Tandy ( Radio Shack) stores that used to be in the UK

then 1/4 W resistors like this will be OK -

E3 Series 480 piece carbon film resistor kit | Rapid Online


or 1/8 W resistors like this :-

Not Found | Rapid Online


the 36 ohm 10 watt resistor you are using should ony be warm if the probe is permanently in contact
with the touch plate

( 5/36 ) X 5 = 0.69 W

which is only 6.9% of its maximum (10W)


John

I am doing this as we speak. So I wanted to throw this out and see if I am thinking correctly. My mill id all metal and the chassis is grounded to AC ground. I have a touch off plate i bought and the back side is non conductive. Just to prove this works I disconnected the AC ground and used the clip lead with 5V on it to connect to the touch off plate giving me and active high on the BOB. The touch plate is .757 high and hard to deal with on X and Y axis. So could i not just jumper my BOB to pull High and then connect the touch plate to input and set mach for active low. When endmill hits touch plate get a ground...

I was thinking about using a printed circuit board that has not been etched for a touch off plate... Since I am going to need this everytime I Auto Z y or x ..

Ideas comments...

Thanks

[john-100]

Hi truckeic

which breakout board do you have ?

Is the spindle connected to the mains earth / ground ?
Or are you using a dremel type of spindle that's isolated from the mains earth ?

connecting an isolated touch plate or piece of copper clad board to the BOB input will ground the input when a grounded tool touches the touch plate or copper board

you can have electrical noise problems when the BOB's input ground is connected to the machines mains earth / ground

John

[truckeic]

Hi truckeic

which breakout board do you have ?

Is the spindle connected to the mains earth / ground ?
Or are you using a dremel type of spindle that's isolated from the mains earth ?


connecting an isolated touch plate or piece of copper clad board to the BOB input will ground the input when a grounded tool touches the touch plate or copper board

you can have electrical noise problems when the BOB's input ground is connected to the machines mains earth / ground

John

I have a Harbor Freight X2 Mill. and yes the spindle is grounded through its bearings and such to ground. When (for test purpose) lifted the earth ground I could use a active high (clip lead with 5v) on the spindle and then a isolated touch off probe. I would like to use the X and Y zero scripts that i have gotten but since the spindle and my part are both ground that won't work. I would assume all these CNC mills are grounded but maybe some of the spindles are not. I do not want the AC ground to be lifted so my best way to make this work is tie the controller ground to the mill chassis and use active low.
I am all ears to find a solution to this if you can offer one.

Thanks!!

[john-100]

which breakout board do you have ?

John

[truckeic]

which breakout board do you have ?

John

Sorry forgot to say...

I have the CNC4PC C11G

[john-100]

now I know it's a C11G

the next question is is it connected to a desktop PC or a motion controller ?

with the C11G you have the advantage of individual pull up/pull down jumpers on each of the five inputs
set the touchprobe input to pull up

with the C11G connected to a desktop PC
the C11G input ground will be connected to the PC's mains earth
the Harbor Freight X2 Mill spindle and table connected to its own earth

an isolated touch plate connected to the C11G input should work

provided you don't have noise problems due to the interaction of the two earths

connecting the C11G input ground to the Harbor Freight X2 Mill table or spindle will form an earth loop

depending on the answers,
connecting the touch plate via an opto-isolator will solve an earth loop problem

John

[truckeic]

now I know it's a C11G

the next question is is it connected to a desktop PC or a motion controller ?

with the C11G you have the advantage of individual pull up/pull down jumpers on each of the five inputs
set the touchprobe input to pull up

with the C11G connected to a desktop PC
the C11G input ground will be connected to the PC's mains earth
the Harbor Freight X2 Mill spindle and table connected to its own earth

an isolated touch plate connected to the C11G input should work

provided you don't have noise problems due to the interaction of the two earths

connecting the C11G input ground to the Harbor Freight X2 Mill table or spindle will form an earth loop

depending on the answers,
connecting the touch plate via an opto-isolator will solve an earth loop problem

John

Connected to a desktop. I am using parellel port.

I have a 4 channel opto isolator.

Do you have a schematic of connecting that up.
I truly appreciate your help

Sent from my XT1635-01 using Tapatalk

[john-100]

this is a very basic diagram to add a PC819 opto isolator to a C11G input

Attachment 421414

if you add a link to your 4 channel opto isolator
I will add more details just for your opto-isolator
some opto-isolator boards have transistors connected to the opto-isolator output transistor



John

PS
a random opto-isolator PCB example

Attachment 421416

[truckeic]

this is a very basic diagram to add a PC819 opto isolator to a C11G input



if you add a link to your 4 channel opto isolator
I will add more details just for your opto-isolator
some opto-isolator boards have transistors connected to the opto-isolator output transistor



John

PS
a random opto-isolator PCB example

Ok This is what I have here:

[john-100]

I have found this circuit diagram for your opto-isolator board
Attachment 421466

the 3K resistor connecting the opto-isolator collector to terminal V1 is higher than I would expect
(if it was near to 300 ohms I would of connected the photo transistors emitter / output GND to the BOB's GND )

if the resistor values on the opto-isolator are correct I would connect it to the C11G like this
Attachment 421468

when the tool touches the touch plate
the LED indicator will be on and the photo transistor inside the "817" opto-isolator will switch on

This connects the BOB's +5V via the 3K resistor to the BOB's input
the printer port pin should switch from a logic low (0V) to a logic high ( +5V)

In Mach 3 set the input to active high


John

[john-100]

looking closer at the photo of the PCB
it looks like the resistors fitted are 1K (marked 102) instead of the 3K shown on the circuit diagram found on line

Attachment 421508

John

[truckeic]

looking closer at the photo of the PCB
it looks like the resistors fitted are 1K (marked 102) instead of the 3K shown on the circuit diagram found on line



John

Great information and great drawing... Thanks I will be hooking this up. I am considering hooking all the inputs to the BOB through the Opto board just to clean things up. How much do you know about Index pulses. I built a Hall effect sensor and I am getting a reading but i am not sure its accurate. MACH3 says one speed and the Index says another.