Retrofitting a 1986 Maho MH400E

The Heidenhain LS403 encoders have a single reference point, so the Index signal only triggers once on the whole length. I have have little idea where in the travel that Index signal occurs, but I am assuming it is within the the hardware end stops (which as you say, trigger the hardware E-Stop condition). I plan on homing off that index.

In your case, unless you reinstall glass scales, on X and Y it would be pretty easy to piggy back a prox sensor or microswitch off the end stop switch on a bracket,and trigger home off a stop block, before the end stop switch gets to it. Not sure where the Z end stop switch is located, but would guess it is similar.



Mark

Usually when hard limits are configured like this, there is a separate home switch used.

Thanks, the proximity sensor in that place seems to be the best solution. And I will use the index on the encoders for more precise homing.

drimaropoylos wrote:

Every time we start the machine we have to home it, how is this done? The limit switches once triggered the machine goes off.
John

If you have the right home sequence set in the HAL file, there will be a "home all" button, and it can home multiple axes simultaneously. I always worry about a crash when some tooling has been left in the machine, so I do each axis one at a time.
You can hit the home button on the screen, or the home key on the keyboard above the arrows. Number keys can select the axes (0,1, 2 3) to select which axis is to be homes.

As for homing by the limit switches, you need to set HOME_IGNORE_LIMITS = YES
on each axis, in the [AXIS_n] stanza of the .ini file.

Jon

The problem is that the limit snitches are hard wired to the estop circuit, so when they activate, they power off everything.
John

I installed the PC, the EXE and the 7i84, so now it is wiring wiring wiring...
,
Unfortunately I cant find my bag of heat shrink.

First up, I just wanted to wire up the 5V to the 7i77, and the field power to both 7i77 and 7i84. I found an error in my wiring revisions. I had planned to wire both those boards to the +24V rail at terminals 200 (+) and 201 (0V). Checking the wiring diagram, there are three 24VDC rails. The one I choose isn't powered until the E-Stop chain is closed.


Since not all MESA pins are reported through the HAL if field power not applied, I am picking that this configuration would cause a LinuxCNC loading error for missing pins.

The 7i77 and 7i84 field power needs to be moved to that other rail between terminals 204 (+24) and 201 (0V), to ensure that they are always powered. Also, I added a field power connection 7i84 TB1-3 to power the second bank of connectors, which I missed before.

Once I get the MESA boards powered, then next step will be to wiring up a temporary E-Stop and Machine on buttons, and configure those HAL functions.
Mark

drimaropoylos wrote:

The problem is that the limit snitches are hard wired to the estop circuit, so when they activate, they power off everything.
John

Well, then you need to add additional switches within the span of the limits for the homing.

Jon

They came up really nice.
John

We do have some experimental firmware for the 7I84 that allows startup and input to work without field power
(just VIN), so you could wire the 24V that's available only when out of EStop to the field power

It does require that the input thresholds be set via LinuxCNC hal pins
since it can't depend on field power being present.

If it works out we will add the option to the 7I76 and 7I77