Endstop do I need a resistor?
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Aha! Good old makerbot... long story, let's just fix it to work.
Step 1: Parallel the switches. All three wires. Like this:
NOTE DO NOT PLUG THESE IN YET, see step 2.
Switch A:
- Ground (black) to ground on Duet (black pin in diagram below)
- Vin (red) to +3.3V on Duet (middle yellow pin)
- Green to Duet XYZ stop (grey pin in diagram below)
Switch B:
- Ground (black) to ground on Duet (black pin in diagram below)
- Vin (red) to +3.3V on Duet (middle yellow pin)
- Green to Duet XYZ stop (grey pin in diagram below)
You can "Y" the wires together any way you wish. Crimp in to same connector splice, etc.
Step2: Modify BOTH endstop boards as follows:
Clip out the "NC" connection on the physical switch.
Now you should get what you want. Either switch pressed (or both) will make index 2 go "Yes".
Delta / Kossel printer fanatic
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@Synapsis said in Endstop do I need a resistor?:
... the past a couple of times the Z-probe wasn't working the bed would crash into the nozzle ...
On my printer I have mechanism hard stops such that the bed cannot push the nozzle more then a few mm which can absorbed by the flex of the X rods. Saved me a few times.
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With these makerbot boards you can remove all of the surface mount components then get a normally closed switch across the outer two connections on the plug.
The surface mounts can be tricky to remove with a soldering Iron and will likely get destroyed doing so.
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With the boards as is there could be additional fault diagnosis on the boards but the added complexity would rarely be used.
i.e. Open circuit is a fault, close circuit is switch not triggered, the voltage that causes a dim LED is switch triggered.
Thinking on it further this could be an SPI board to achieve that...
Edit; could an SPI board be checked regularly for an ok signal?
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@Danal said in Endstop do I need a resistor?:
......
Clip out the "NC" connection on the physical switch.
....Thanks for the fix but one question will it be a NO or NC because if I cut the NC
wouldn't it become a NO?zapta 16 Apr 2020, 06:33
I have 2 linear guides on a 20x20 profile so I have no flex what so ever only thing to move it the head mount and head.
but like you were saved I wasn't saved . 
DocTrucker 16 Apr 2020, 08:57
I had tried with a tester and I have a closed circuit until I would press one of the two switches so thought the board had a internal resistor to detect it as NC.
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OK so I see where I was mislead or better misread. On the Wiki Connecting endstop switches I read
"Microswitch
This applies to a bare microswitch, not to a microswitch on a board with a LED.
this i what i didn't see.Duet WiFi, Duet Ethernet and Duet Maestro: connect the switch between GND and STP/IN. These are the outer 2 pins of the 3-pin connector. Note: this is not the same as on RAMPS."
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@Synapsis if you clip the leg like picture you will get a normally open switch, which is a poor choice for a limit switch as it can't detect the most likely failure of a wire breaking or plug pulling out. I remove all of the surface mount components and the outer two connections on the plug behave as normally closed, which is what you want for a limit switch or z-probe.
Running 3 P3Steel with Duet 2. Duet 3 on the shelf looking for a suitable machine. One first generation Duet in a Logo/Turtle style robot!
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@DocTrucker said in Endstop do I need a resistor?:
@Synapsis if you clip the leg like picture you will get a normally open switch, which is a poor choice for a limit switch as it can't detect the most likely failure of a wire breaking or plug pulling out. I remove all of the surface mount components and the outer two connections on the plug behave as normally closed, which is what you want for a limit switch or z-probe.
Exactly what I thought, as I do want NC. Do you have a photo of how you did it?
Thanks for your help.
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@DocTrucker said in Endstop do I need a resistor?:
@Synapsis if you clip the leg like picture you will get a normally open switch,
No, he won't. The circuit effectively inverts the behavior (note, not logic, behavior).
And if he wires in parallel and doesn't clip it, triggering one switch WILL CROWBAR THE OTHER SWITCH, which could potentially damage the board to which they are plugged in.
Think of two of these in parallel, with one of them triggered. That combination just connected VCC DIRECTLY to ground.
Delta / Kossel printer fanatic
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@DocTrucker said in Endstop do I need a resistor?:
I remove all of the surface mount components and the outer two connections on the plug behave as normally closed, which is what you want for a limit switch or z-probe.
This will ALSO work. By removing ALL the components, this is a simple switch again, and you are absolutely correct, the outer two wires (com and nc) are what you want.
In fact, I'd remove the switch from the board.
AND... In that case the wiring is sequential, not parallel.
- Duet GND to outer terminal (doesn't matter which) on switch A
- Other outer of switch A to outer on switch B
- Other outer of B to TRIG on Duet
Forms a big "loop" between Trig and Gnd.
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Thanks Danal and DocTrucker for the help.
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Ok one last question, I hope, end stops now working ok took out the R1 and R2 and it works, question now if I use M581 Z2 S1 T0 C0 this will send a M112 and reset the board if I use T1 I would get a pause (which I want ) but this only works while printing?
I didn't want to use a trigger because there maybe a little delay before executing the command.
Am i forced to use T0? -
@Synapsis said in Endstop do I need a resistor?:
Ok one last question, I hope, end stops now working ok took out the R1 and R2 and it works, question now if I use M581 Z2 S1 T0 C0 this will send a M112 and reset the board if I use T1 I would get a pause (which I want ) but this only works while printing?
I didn't want to use a trigger because there maybe a little delay before executing the command.
Am i forced to use T0?What is your goal? When homing, the printer will stop itself if it hits either of those endstops.
Do you want it to pause if it hits one while printing? Or something else?
Delta / Kossel printer fanatic
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@Danal said in Endstop do I need a resistor?:
Think of two of these in parallel, with one of them triggered
ouch; is that a common schematic for all those endstops with leds?
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@bearer said in Endstop do I need a resistor?:
@Danal said in Endstop do I need a resistor?:
Think of two of these in parallel, with one of them triggered
ouch; is that a common schematic for all those endstops with leds?
Yeah, ouch indeed. I'm glad you see it as well.
AFAIK it is common to anything that has that "Design by MakerBot" in one corner. Including BigTreeTech and several other retail/channel brands. Meaning, VERY common.
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@Danal said in Endstop do I need a resistor?:
@Synapsis said in Endstop do I need a resistor?:
Ok one last question, I hope, end stops now working ok took out the R1 and R2 and it works, question now if I use M581 Z2 S1 T0 C0 this will send a M112 and reset the board if I use T1 I would get a pause (which I want ) but this only works while printing?
I didn't want to use a trigger because there maybe a little delay before executing the command.
Am i forced to use T0?What is your goal? When homing, the printer will stop itself if it hits either of those endstops.
Do you want it to pause if it hits one while printing? Or something else?
They are a backup in case during homing the Z-probe for some reason does not work, so I want it to stop the movement of the bed but without having to reset the printer by recycling it off/on for example. There will be one near the two lead screws.
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@Synapsis said in Endstop do I need a resistor?:
@Danal said in Endstop do I need a resistor?:
@Synapsis said in Endstop do I need a resistor?:
Ok one last question, I hope, end stops now working ok took out the R1 and R2 and it works, question now if I use M581 Z2 S1 T0 C0 this will send a M112 and reset the board if I use T1 I would get a pause (which I want ) but this only works while printing?
I didn't want to use a trigger because there maybe a little delay before executing the command.
Am i forced to use T0?What is your goal? When homing, the printer will stop itself if it hits either of those endstops.
Do you want it to pause if it hits one while printing? Or something else?
They are a backup in case during homing the Z-probe for some reason does not work, so I want it to stop the movement of the bed but without having to reset the printer by recycling it off/on for example. There will be one near the two lead screws.
Got it.
During HOMING, it Duet allows both a Probe and Endstop defined on the same axis. I believe (double check) that either one stops the axis. This would mean no triggers or macros needed.
During PRINTING, it would need to be a trigger. They do, by the way, trigger in milliseconds, plenty quick enough to prevent a crash (depending on what the triggered macro does).
There is a bit of a dilemma on "kill it instantly" vs "pause it so it does not require a reset, and can be restarted". Consider the case of a long move. Any form of pause must occur at move boundaries. If this is a long move that hits the switch , there is no correct answer to pause/restart. This has nothing to do with the switches or the triggers or etc. It is literally the nature of G-Code.
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@Danal said in Endstop do I need a resistor?:
Ok still looking for the correct info but from what info i have It should work maybe.
Doing a M119 I get
Endstops - X: not stopped, Y: at max stop, Z: not stopped, Z probe: not stoppedSo I would think there are two on the Z axis also because i have a M574 Z2 S1 to define it. When I tried homing i triggered the switch but it did not stop the homing the Z probe did as usual.
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Wired the way the two switches are wired, they are showing as "Z: not stopped". That should change to "Z: Stopped" whenever you click either one.
Delta / Kossel printer fanatic
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@Synapsis said in Endstop do I need a resistor?:
M574 Z2 S1
Z2 is incorrect. Z2 means "max numeric value of z". Z1 means "minimum value". That is what you should be running.
Note: This has nothing to do with whether the bed is "up" or "down" in relation to the floor... just whether the numbers get smaller or larger.
Delta / Kossel printer fanatic
