Moving from Soft limits to hard limit switches

[PeteJ]

Intried a variety of things today and I cannot get the X axis to home properly off of the limit switch. It trips the switch, I get the 325 error and and will not clear the limit trip and back off. The Z axis works fine. I have seen several posts on this but cannot seem to find a resolution other than use soft limits.

It worked fine with the old Centroid 11 control, the issues started after I upgraded to the Allin1DC. I was told by support (that i paid for) that the issue was the older limit switches not responding fast enough and the solution was to install the Automation Direct switches, which has not worked.

Any ideas or suggestions are welcome.

[cncsnw]

So, you want to home X+ and Y-.

Therefore you need to edit your cncm.hom file to use "M92/X" and "M91/Y".

It sounds like you have your direction reversal settings sorted out correctly, so that jogging X+ makes the table move left, and jogging Y+ makes the saddle move toward you.

If you get limit errors while trying to home, then there is something wrong with the input numbers you have entered on the Machine Configuration -> Motor Parameters table, or with the wiring of the switches to the PLC input terminals.

Post a fresh report, and a current picture of your input terminal connections.

[PeteJ]

Attached is the report. For the input terminal connections, do you want the limit switches or the motor connections?

[cncsnw]

Your Y limit switch input numbers are still entered wrong:

Code: Select all

Axis  Label  Motor                Encoder      Lash Comp.        Limit          Home      Dir  Screw
             revs/in              counts/rev.  (inches)          -     +        -     +   Rev  Comp
1     X     10.0081070000000008      8000        0.0004          2     1        2     1   Y     N
2     Y     10.0046999999999997      8000        0.0032          4     3        4     3   N     N
3     Z      9.9950229999999998      8000        0.0002          6     5        6     5   Y     N

Since you do not have direction reversed on the Y axis, the Y axis switch input numbers should read "3 4 3 4".

Then you will need to make sure you have wired the Y minus switch (the one that trips when the saddle moves toward the column) to INP3; and the Y plus switch (the one that trips when the saddle moves toward you) to INP4.

[PeteJ]

Your Y limit switch input numbers are still entered wrong:

Code: Select all

Axis  Label  Motor                Encoder      Lash Comp.        Limit          Home      Dir  Screw
             revs/in              counts/rev.  (inches)          -     +        -     +   Rev  Comp
1     X     10.0081070000000008      8000        0.0004          2     1        2     1   Y     N
2     Y     10.0046999999999997      8000        0.0032          4     3        4     3   N     N
3     Z      9.9950229999999998      8000        0.0002          6     5        6     5   Y     N

Since you do not have direction reversed on the Y axis, the Y axis switch input numbers should read "3 4 3 4".

Then you will need to make sure you have wired the Y minus switch (the one that trips when the saddle moves toward the column) to INP3; and the Y plus switch (the one that trips when the saddle moves toward you) to INP4.

I will make the above changes and report back.

One thing to note is that the z works fine but and never gets to the Y. When running the home program it first errors out on the X axis, it trips the switch and will not back off.

[cncsnw]

One thing to note is that the z works fine but and never gets to the Y. When running the home program it first errors out on the X axis, it trips the switch and will not back off.

When this happens, there will be an error message -- or two or three lines of error messages -- in the message box in the upper right corner of the screen. Those messages are important, because they tell you why the homing macro cannot continue.

Let us suppose, hypothetically, that your homing sequence gets to the line with "M92/X"; and that X moves in the plus direction (table moves left); and that it moves all the way to a home/limit switch; but then the error message "407 X- limit (#50002) tripped" appears in the message window, followed by "325 Limit: job cancelled".

That would mean that your limit switches are wired backwards. Because INP1 needs to be the X+ limit, and INP2 needs to be the X- limit, you have to connect the wires so that the switch that trips when the table moves left is wired to INP1; and the switch that trips when the table moves right is wired to INP2.

As an alternate hypothetical, let us suppose that the homing sequence moves Z up to the switch, then back down a short distance, and then the cycle is canceled without moving X at all, and the error message in the message window is "Switch failed to clear, homing cycle canceled". That would mean that your Z+ switch has too much hysteresis: the amount that the axis needs to move back down after tripping the switch, before the switch clears again, is excessive. In that case, you could either replace the switch with a better one, or increase the distance in Parameter 180.