Tandem Y Axis not working on 7i76E

I probably should have mentioned this and totally forgot.

My motors are actually on the back of my Y, Y2 and X Axis.

I suspect this is where the confusion plays out.

I noticed this for the -320 value for STEP_SCALE. The scale is correct based on the drives being on the back of my unit.
So, how would I handle this scenario?

 
 

Hi Folks,
Thank you everyone for your feedback.

So far I am still unable to get my Y and Y2 Axis homed. Very frustrating. 
For both Y and Y2 Axis I have the drives mounted on the rear as I indicated in a previous image.
I have single inductive sensors mounted on each Y Axis. Each Y and Y2 sensors are mounted in the front of the machine at 790mm from the rear of the machine. Only one sensor per axis.

790mm is the absolute max that I can travel in the Y direction. However, after Y and Y2 are homed I need them to move 228mm towards the rear of the machine.

What is happening now, is the machine is homing in the correct direction however, both Y and Y2 axis simply disregards the inductive switches and continues in a positive direction instead of reversing.

Attaching my current config files.
 

As Tommy says your home switch must remain triggered to end of travel.
I have found it helpful to significantly reduce homing velocities until you know the directions are all correct. That lets you see what is going on

The homing velocity is set to an incredibly slow paint-drying speed as it is now.

I think what would be helpful to me and perhaps others would be to create a visual image of this setup. Similar
to the one that I included previously. One with only one switch and an optional image where the drives are located on
the rear.
I am using 1/2" fender washers with the slow speed I'd almost expect an immediate stop.

Here are a couple of photos of "Woody".

 

 

One other note/question that I have regarding the documentation, is the plural word LIMITS correct here or should it be singular LIMIT?

• A<->B is the negative soft limits (MIN_LIMITS) = 0 units
• B<->C is the home_offset (HOME_OFFSET) = -0.7 units
• B<->D is the positive soft limits (MAX_LIMITS) 10 units 

if you check the homing configuration docs, it says the homing sequences should be sequential with no gaps. You start at -1 and you don't have a 0 in the sequence. Renumber so you use -1,0,2,3. Normally, you want the z to home to top of travel  to get it safely up in the air before moving X or Y so make it 0.

Its a nice looking machine but you are setting up to cause a massive crash. Two of us have told you to ensure the switches stay triggered to the end of travel. This lets linuxcnc know which side of the triggering edge you are on at the start of travel.

If homing commences while the prox sensor is between the washer and the end of travel, it will assume it has to continue towards the end stop to find the triggering edge and crash. Replace the washers with strips of steel. You don't need any adjustment to position because you can adjust the final position in  software using HOME_OFFSET

Actually they changed homing sequence after I set up the homing of my gantry machine to number in absolute values so I might be wrong.
say you went 0=Z, 1 = X, 2 =Y, 3=A
But because Y is a joint axis, you then change them to -2 so Y = -2

Thanks Rod, I'll give your suggestions a try.

Note that Y and Y2 Axis cannot travel past the washer and realistically if homing is functioning properly.
This setup will change once I get this setup functioning properly.
I will not let the speed become so high during homing that it races thru the axis ends.

Maybe I should rethink my design and or perhaps move to another controller OS. The reason why I selected
LinuxCNC is I've been a UNIX person for the last 30 years. Been printing and MPCNC'ing for the last 6-7 years.

Or even better maybe I should consider adding two more switches so that I'd have a switch at each end of the axis.
I believe that I have some extra switches laying around.

In any case thank you to all of the feedback, I appreciate it.