Z-axis homing - Y-axis tuning - ClearPath servo firmware updates

Those should work, I use something similar on most of my machines. They only work with steel, not aluminum.

If memory serves
Brown is +
Black goes to mesa (signal wire)
Blue is -
The sensor usually has a wiring diagram on the sticker

The easy way to test this
Hook up power leave the signal wire unplugged.

Put a piece of steel by it, light should light up on the back of it.

Now plug the signal into the next open digital input on the mesa

Move piece of steel and make sure mesa led lights up (or turns off if it's on by default)

You will need to configure your hal file so it's looking at the right input. Chances are if you used pnf config you did this without knowing it.

Now when you try to home z will go first. Shake a piece of steel in front so it turns the sensor on and off about once a second until the y axis starts going.


If it doesn't let us know what's going on and we will help more.

Hello,

I just thought I would give an update. We managed to get one of the switches hooked up properly and the z-axis homing working. Woohoo! Thanks to everyone for their help and suggestions and taking the time to read my surely nonsensical ramblings. You helped me a lot.

I played with the motors a bit and set the y-axis motors to increase the stiffness in the fine-tuning which hopefully helps with some of the dots. It doesn't seem to vibrate much after we simulated the y-axis weight on the x-axis and did auto-tuning in the ClearPath MSP software and then copied the config to both of the y-axis motors. I'll try adjusting the I or the deadband after that process and see if that helps now because I only tried those before doing that to try and fix the vibration issue and it didn't work. Auto-tuning on the x-axis simulating the y-axis as best we could is what helped with that.

A note that for the LJ18A3-8-Z/AX inductive proximity sensor switch I hooked the black wire to the field input 8 which was the first available digital input. I'm not sure if 0-3 were digital because they weren't hooked up to anything. The other switches were hooked up to 4-7 and in a video I saw someone say they were capable of analogue so I used 8 instead. I thought I remembered reading something in the Mesa board manual about all of them being capable of analogue but maybe I'm not understanding something properly there which wouldn't be surprising. But it works like this so I don't think I'm going to worry about it. I hooked up the blue wire to the field power ground on the Mesa board and the brown wire to the power on the same orange field power block. This seemed to be the right way. The light on the switch is always on until it detects metal. This actually works.

Now, here is another big problem I was having. The MAX_VELOCITY for the z-axis was set to 0 in halshow. After spending countless hours trying to figure out why the z-axis won't move I started looking at everything in halshow and discovered that the others were at 116 but the z-axis was 0. I eventually traced it to a line the pendants hal file. There are some lines commented out for an extra axis but it uses the A axis. I realized one of the lines was for MAX_VELOCITY on JOINT_3 which is my z-axis and once I uncommented that halshow showed 116. I don't know if I need the other lines but things seem to be working from what I can tell so hopefully it's ok.

Another issue I'm having now is that I realize that when the machine is powered off or loses power that the z-axis falls down. I'm not sure if there's an ideal way to fix this yet but I don't want to wreck anything or anyone if the machine suddenly loses power for some reason. Who knows when the power could go out. When the x and y are at home the bit could potentially have something under it since it's over the work area still so I don't think it's ideal to just put a block of wood under it or use a little piece of wood to jam in the space under the spindle sliding part, like my dad was doing. Especially if I forget to put it in there which is quite likely sometimes. Is there any other way of dealing with this that I can implement in this particular setup? Or do I just have to code something to tell me when I shut the computer down to put a block of wood under it?

Thanks again!

Sorry, looks like I lost a post or was distracted. The 7i76e which I saw you were using should use PNP prox sensors and your link was NPN.
You can use NPN sensors with a 2.2 k 1 W pullup resistor.

You  may  be able to set up a brake with your servo drive on the Z axis. 

Oh, no worries. Thank you for the reply!

Hmm, so the thing I'm using shouldn't actually work or is it just going to be damaging in some way if I run it like that or cause other issues then? It does seem to be working the way I hooked it up but if it's going to wreck something maybe it's not good to run it like that.

Also, where should I place the resistor? I'll see if I can figure out how to go about doing that if it's something I should be doing to prevent damage somehow.

A brake sounds exactly like what I might want to use too. I'm guessing there are specific types or brands I should be looking for to make it brake when the power is lost to prevent the spindle from falling. I have absolutely no idea how to determine if it's going to be compatible with things or even how to go about hooking one up but I suppose that's some more things I'll have to research.

Thank you!

If it's working you are probably fine. Those sensors have resistors to limit current. Mesa is well designed so it should protect itself.


While a brake would work, might want to try a spring or counter balance first as those are easier/cheaper unless their is a drop in servo with brake.

Another option would be have your controls and pc on a UPS and to have the machine job to a "park" location where it lowers z before turning off.

Oh, no worries. Thank you for the reply!

Hmm, so the thing I'm using shouldn't actually work or is it just going to be damaging in some way if I run it like that or cause other issues then? It does seem to be working the way I hooked it up but if it's going to wreck something maybe it's not good to run it like that.

Also, where should I place the resistor? I'll see if I can figure out how to go about doing that if it's something I should be doing to prevent damage somehow.

PNP sensors are suggested for 7I76E inputs as the inputs work by sensing a positive
input voltage. PNP sensors supply a positive voltage when the output is active.
NPN sensors connect their output pin to common/ground when activated.

Some NPN sensors will work with the 7I76E because they have built in pullup resistors,
but for reliable operation it best to add an external 2.2K 1/2W pullup resistor on each
NPN output to guarantee a valid high state. The pullup resistor goes from +24V to the NPN
sensor output.

You can check switch operation by measuring the voltage in both on and off
states at the 7I76E input. With a 24V supply I would make sure its >20V
when high and < 4V when low.

There is not any real possibility of damaging the 7I76E inputs unless
you continuously apply voltages > 48V to the inputs.