Questions regarding configuring limit switches for Allin1

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cncot
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Questions regarding configuring limit switches for Allin1

Post by cncot »

Gentlemen:
Questions regarding limit switches:
First:
I need to make some limit switch cables for my Allin1.
I have 4 conductor 24 ga overall shielded cable.
The drawings call for minimum 22 gauge.
Can I get away with this or do I have to buy cable? Aren't the signals only milliamps?
I am replacing an Anilam 1100 on a Bridgeport series 1.
The cable lengths are 6-15 feet.

Second:
Do I ground both ends or one end (the drive end?) of the shield?

Third :
If a short part of the run outside the control cabinet has no shield or a whole axis is unshielded, then what are the potential resulting problems/symptoms?

Fourth:
The mill X and Y axis existing limit switches are a single NO switch closing on both pos and neg travel limits.
so +X and -X are the same switch! same for Y, so I have only 4 wires....
How do I configure the wires at the H10 connector?
How do I configure the software?

Fifth:
The Z axis has 2 switches but only 3 wires: the commons are shared.
How do I configure the wires at the H10 connector?

Sixth:
My DC1 drive has 2 limit switch inputs. Your/(or mine; when I get it) Rotary axis has only a home switch.
I cannot find the documentation for hooking up a home switch to the DC1.
How do I wire it (to the plus, I assume) and configure the software?

Warm Regards, Mike
polaraligned
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Re: Questions regarding configuring limit switches for Allin1

Post by polaraligned »

I used SOOW wire for my limit switches on my Bridgeport Series II. It has a tough rubber jacket that is oil and weather resistant. I used 18 ga and it is widely available, even the big box stores sell it by the foot. You can get it in 2 or more conductors. It is going to be a lot tougher than anything 24 ga. Been running my current machine for 8 years and never an issue with no shielding. My machine before this was running Mach and never issue with SOOW for limits on that either.
That said, I have no problems and my DC3IOB uses 5v for the limit switches, you are probably running 24v by default with the Allin1 so you really should have no problems with noise.

I would change the switches to NC as it protects you against a wire failure. You only need a minimum of one switch on each axis and you can use soft limits on the other end of travel. You can get very good quality NC switches on Ebay for $25 to $30 each. Check the switches you have as they often have the option of wiring for NO or NC. Open them up and have a look. Configure just like on the schematic.

As for the DC1, forget the limit switch inputs. See my recent thread on the DC1.
For homing, just run the homing switch for that axis into an extra input and then set that input number for homing on the same CNC12 screen that you set the other axis limit and homing inputs. For example, if you are using input 13 for homing in the + direction, set the + homing to 13. You can then M92/A and M26/A to set home to that switch. Use a NC switch.

With 3 wires for the Z +/- switches, just connect on wire (the common wire) to one side of each switch, then connect the other Z terminals to their respective Z+ and Z- limit inputs. The common shares that one wire.
cncot
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Re: Questions regarding configuring limit switches for Allin1

Post by cncot »

Thanks, polaraligned

What is going to happen when the computer sees a x limit switch activate on BOTH travel ends but it does not know which end ?

My cables are now finished complete assemblies all completely in flex conduit and connected with Military connectors. I can not use SOOW. I understand why you recommend it.
Why does the factory specify minimum 22 gauge? I have already made some cables with 24 ga and don't want to tear them up...
Mike
polaraligned
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Re: Questions regarding configuring limit switches for Allin1

Post by polaraligned »

I am not sure if CNC12 will consider the direction of travel when the switch trips. Maybe someone else can answer that. If it were me, I would change it so it only trips on whatever end of travel you want to home to. I assume that this switch is in the middle of the saddle, and the trip dogs are on the ends of the table, kinda like the setup for a power feed on a manual BP mill. Hard to give suggestions without a picture of what it looks like.

The 24 ga will be fine. Don't sweat it.
cncsnw
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Re: Questions regarding configuring limit switches for Allin1

Post by cncsnw »

What is going to happen when the computer sees a x limit switch activate on BOTH travel ends but it does not know which end ?
It will be unable to move in either direction, so you will be stuck on the switch until you turn the ballscrew with your hands. That precludes homing, because the control cannot back off the switch.

That is why you will have to make the one switch be the limit and home switch for one end only, and do without hardware limit protection for the other end (until you can afford to install a second switch, anyway).

Decide which way you want to home, and set the switches up for that direction. For example, if you use the default behavior of homing Z+, X-, Y+, then you have to make your lone X axis switch trip at the X- end (table-right), and the lone Y axis switch trip at the Y+ end (saddle-forward). You have to rely on the software travel limits to prevent going too far in the opposite directions.

As polaraligned noted, you will need to rewire (or replace) the switches so they are normally-closed. With an Allin1DC, just inverting in software is not an option, because the limit inputs are hardware inhibits.

On that note, you will need to turn on the hardware limit defeaters for any axis directions that lack limit switches (X+ and Y- in the example here). The limit defeaters are the DIP switches on the left edge of the Allin1DC.

Before you can know whether to connect your X- switch to INP1 and defeat INP2, or to connect your X- switch to INP2 and defeat INP1, you will need to find out which direction your motors and encoders turn. That will determine whether "Direction Reversal", on the Machine Configuration -> Motor Parameters table, needs to be No or Yes. If Direction Reversal is off (No), then the minus switch goes to INP1, and INP2 would have to be defeated. If Direction Reversal is on (Yes), then the minus switch goes to INP2, and INP1 would have to be defeated.

The same logic applies to the Y axis with INP3 and INP4. If Y is not reversed, then the minus switch goes to INP3 (or INP3 is defeated since there is no minus switch) and the plus switch goes to INP4. If Y is reversed, then the minus switch (if any) goes to INP4, and the plus switch goes to INP3.
cncot
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Re: Questions regarding configuring limit switches for Allin1

Post by cncot »

Thanks, quite clear!
On a Anilam/Bridgeport mill, it seems I might be able to add 2 more switches to the right hand existing limit switch brackets on the knee casting rather than make new brackets on the left. Does anyone know where I might find an example design?
The motors/encoders are wired to turn clockwise viewed from the shaft and count up with a positive voltage applied to the armature.
So is direction reversal to be set to off/no?
If a clockwise motor as I described caused , say the z axis, to move in the negative direction as perhaps a mechanical reversal would, does this imply that direction reversal should be set to yes? Or is that intended to correct for an encoder wired to count up the wrong way?
Thanks, Mike
cncsnw
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Re: Questions regarding configuring limit switches for Allin1

Post by cncsnw »

The encoder direction has to be matched to the motor-power direction per wiring. Once they are matched, the software "direction reversal" setting can be used to match motor/encoder rotation to the desired axis travel direction.

If you tested the direction of encoder counts and the direction of motor rotation using the Anilam control, be aware that Centroid may be different. Just defer connecting limit switches until you have a motor and encoder connected to the Allin1DC so you can find out for sure which way it will turn.
cncsnw
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Re: Questions regarding configuring limit switches for Allin1

Post by cncsnw »

For a Centroid control, positive encoder counts (counting up) are when the channel on pins 5 and 8 of the DE9 connector leads the channel on pins 4 and 7. Whether you call those channels "B" and "A" respectively is somewhat arbitrary.

It is preferable, for consistency, that a positive encoder count corresponds with CCW rotation looking at the shaft face of the motor (i.e. right-hand rotation).

Counterintuitively, positive output from a Centroid DC servo drive is a negative voltage/current from the plus terminal to the minus terminal. So, if you test motor rotation using a known DC source (e.g. a car battery or charger) you should expect the opposite rotation when you hook it up to the drive.
cncot
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Re: Questions regarding configuring limit switches for Allin1

Post by cncot »

Thanks, Still confused!
I did not test the encoder with the Anilam, but with a CALT encoder counter/encoder bench test instrument from China Encoder during cable design/assembly. I put the motor(s) on a Bench power supply (+ to +....) thereby turning CW facing the shaft, then the counter counts up.
I found this from some reference I found somewhere in Centroids web.(CW = UP)
I did the first bench test and found the encoder counts up on the Centroid allin1 when manually turning the shaft CW as perviously stated.
So do I turn on the Motor reversal or not?, Or as you say If turning CW the motor moves the linear stage in the + direction and that results in counting up......??? I can check this by hand cranking the stage and watching the motor for CW rotation. Now looking at the Ballscrew belt, etc., I am almost certain CW moves the stage in the + direction
I would rather configure it right before moving the stage by servo...
I am at least several weeks away from bring able to power a motor via servo now...
Regards, Mike
polaraligned
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Re: Questions regarding configuring limit switches for Allin1

Post by polaraligned »

cncot wrote: Thu Apr 15, 2021 6:37 pm Thanks, Still confused!
Wire the encoders per the Centroid schematic. Connect the motor + and - voltage to the All-in-one and connect encoders. Issue a motion command via the MDI. If the motor responds and stops, all is good. If the motor either gives a position error or goes into runaway, reverse the + and - power leads to the motor and repeat motion command. It should work fine then. This test assumes you don't have the motor mechanically connected to your machine so no damage could be done in case of a runaway. Don't worry about direction reversal until you get motor on the machine and connected to your drive pulleys. Once on the machine, do a slow move and see if the table moves in the proper direction, eg. to the right for a negative X move, etc. If the motion is backwards, then change the motor reversal direction in the CNC12 software and you will be good to go.
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