Endstop and probe wiring help

you can do all home switches to one input

net all-limit-home <= parport.0.pin-10-in-not

here's the rub. i dont have enough inputs for my parallel port to do everything that i need to do.

it seems counter intuitive to have your joints
separated by default and only slaved after homing.

System integrators can allow joint jogging prior to
homing with hal logic that switches the
[JOINT_N]HOME_SEQUENCE items. This logic should also assert
the motion.homing-inhibit pin to ensure that homing is not
inadvertently initiated when joint jogging is
enabled.

net sync12_enable <= user_panel_enable
net sync12_enable => joint.1.jog-enable 
net sync12_enable => joint.2.jog-enable

net sync12_scale  <= user_panel_scale
net sync12_scale  => joint.1.jog-scale 
net sync12_scale  => joint.2.jog-scale 

net sync12_counts <= user_panel_counts
net sync12_counts => joint.1.jog-counts
net sync12_counts => joint.2.jog-counts 

$ sim_pin sync12_enable/mode=Toggle \
          sync12_scale \
          sync12_counts

dgarrett wrote:

1) Joints are prime movers (typically motors).

2) Joints may be moved individually in 'joint' mode
but there are NO built-in provisions to 'slave' the
motion of multiple joints.

Clive wrote:

Have you thought about a second PP as then you would have 10 inputs:)

pl7i92 wrote:

you can do all home switches to one input

oddwick wrote:

Thank you so much for such an informative reply! that really helped put a lot of things in perspective. i understand the principle of joints and axis and i figured as much where linuxcnc is a general framework.

dgarrett wrote:

1) Joints are prime movers (typically motors).

2) Joints may be moved individually in 'joint' mode
but there are NO built-in provisions to 'slave' the
motion of multiple joints.

what i dont understand tho is why the individual joints of an axis would ever need to be handled separately. it may be that only being familiar with cartesian machines, my understanding of an axis was a joint or multiple joints moving in concert to produce motion on the specified axis. aside from very specific instances and times(like in my case homing a gantry with 2 joints on y axis), why would one ever need to move only one joint at a time? could you give an example by chance? im having a hard time wrapping my head around the logic of it...

Clive wrote:

Have you thought about a second PP as then you would have 10 inputs:)

The thought actually crossed my mind, but then i would need another controller entirely, which would make 4 controllers for 2 machines.

pl7i92 wrote:

you can do all home switches to one input

the problem is that i think that with a gantry on 2.8, since there are 2 separate joints homing simultaneously, that wouldnt work. in theory at least, both should hit the home switch more or less at the exact same time.

at least for the time being i think i am going to switch out my estop for z home, although i don't like relying on only software safety.

is there a way to conditionally assign pins or parport inputs in linuxcnc? that would be nice if one could say that while axis n is homing, then pin x is a home switch, but while running, then pin x is an estop, probe, limit, or whatever.

oddwick wrote:

and now i cant jog the y axis until i home it. and if i try to jog the z axis, instead it moves y1 which is not only disastrous for a gantry, you can well imagine how that goes over in a stall situation with your bit still in the piece!

Todd wrote:

Yes, it is possible to use one or more inputs for multiple things, depending on what the different uses are. The E-stop would not be an an option for this, since it needs to be active all the time. But probe or limit can both share pins with the home switch and I'm sure some others things could share as well. In fact it is fairly normal practice to have the home and limit switches share. What other inputs are you need?

Todd wrote:

The separation of Joints and Axis generally makes more sense with non Cartesian machines where the Joints and their movements may have no direct correlation with the XYZ axis movements (for example a robot arm with all rotating joints.)

I can think of one tortured example of a Cartesian machine where you might need to move individual joints separately. Imagine a gang router with 4 parallel Z axis. Normally you would want all 4 spindles to move up and down together as a single Z axis. But when you need to change tools you will have to readjust the depth on each spindle separately or maybe you need to compensate for varying material thicknesses of the parts placed on each spindle.

Todd wrote:

Part of your problem trying to jog in joint mode before you home the machine is what joints you have assigned to which axis. It sounds like you have joint0 assigned to X (good), joint1 assigned to Y1 (ok), joint2 assigned to Y2 (problem) and joint3 assigned to Z (problem).

Most user interfaces in Linuxcnc assign joint jogging buttons to their "normal" Cartesian axis equivalents. Joint0-X, Joint1-Y, Joint2-Z, Joint3-A... So when in joint mode before you home the machine, when you press the buttons that would normally jog the Z-axis you actually jog joint2 (one of your Y axis motors). I'd suggest switching joint 2 and 3 so that joint 2 is the Z-axis and joint 3 is your 2nd Y-axis.