How to wire 5v end stops into 7i77 input

hello everyone, I am working on a hurco km3 retrofit and am having trouble figuring out the end stock switches. I have found the wires that are an active +5v normally and when tripped go to 0v. But when looking through the 7i77 documents it looks like the field power sets the threshold for the inputs. So am I correct to think that to get the mesa card to register the end stop input it would need to read a high signal something like +14v? And it looks like to read a low it needs to be something like +8v but not zero? If this is correct how do I wire that up? I did get a pack of opto isolators thinking I will have to use those. I will add a video of what I am working on hopefully shedding some light on what I am trying to do and the problems I am having.

Sorry if these are dumb questions, I am figuring this all out as I go. Thanks for any help you guys can give!

According to the blurb on the store page:

"Inputs can sense 5V to 32V signals and the outputs can switch 5V through 28V signals. Maximum output load is 300 mA."

store.mesanet.com/index.php?route=produc...oduct&product_id=120

You should be good to go.

I saw that too but I don't think its working because my field voltage is +24v. If I was using a lower field voltage like +12v then a 5v signal would suffice. I also have tried to hook up directly the 5v to the input but the built in 20k ohm resistor pulls it down to 4.5v.


This is copy and pasted out of the manual for the 7i77.




The 7I77 field inputs have a nominal input resistance of 20K Ohms to field power
ground. 7I77 inputs sense positive input voltages above a preset threshold. For best
general purpose use, default input threshold is 50% of the field power supply voltage with
10% hysteresis. That is with a 24V field voltage an input must be brought to 60% of 24V
= 14.4V to be sensed as high and then brought to 40% of 24V = 9.6V to be sensed as low.
These accurate thresholds and hysteresis allow high speed field signal detection while
maintaining excellent noise immunity.

Are the end stops mechanical switches or proximity switches?
If they are mechanical, it might be easier to just re-wire them
If they are proximity switches, do you have a part number?

They are mechanical for the z axis and proximity for the x and y axis. I will go take the cover plate off one of them later today and see if I can get a part number. I was hoping to keep the wiring in place though because it feeds through the drives so when you hit a limit on one of the axis it stops the drive itself from moving in that direction anymore. So as it sits the switches are doing their job but I need the feedback into my Mesa card so I can home the machine with the switches.

If i understand correct the moment you hit the switch the motor is disengaged. How do you expect lcnc be capable to move the motor back to make homing cycle?