On Wednesday 10 April 2019 13:29:54 Gene Heskett wrote: > On Wednesday 10 April 2019 12:47:23 John Dammeyer wrote: > > Hi Andy, > > See below. > > [...] > > > > The question then is whether or not the system, when starting > > > > can/will > > > recognize an input which is a unit present signal. > > > > > > This is a solved problem :-) (I have exactly the same 4th axis as > > > you) > > > > > > I have a loop of wire on two spare pins on the connector where the > > > 4th axis plugs in to the machine: > > > This drives an input on the STMBL. The STMBL HV enable is only set > > > (HAL Logic) if this input indicates motor-present. > > > > My HP_UHU drives have that feature built in. The encoder connector > > has to have a jumper to show the encoder is connected. Probably to > > avoid a runaway condition. > > > > > I just accept having an A axis display even when the axis isn't > > > connected. And the machine will f-error if you try to move or jog > > > it.
I could tolerate that. > > I'm testing with both MACH3 and LinuxCNC so I can write up a neat > > little conversion document that takes a parallel port BoB based > > system from MACH3 into LinuxCNC with minimal pain. In the MACH3 > > system, on my CNC router, when I tell the open loop stepper > > controlled axis to home all that MACH3 does is zero out the DRO. > > > > But Gene has a home switch on his rotary indexer. Now thinking > > about it I think the solution might be simple. When he pulls the > > indexer off the mill he has to unplug the encoder cable. If he's > > using safe type limits then the switch is normally closed and a home > > (or limit) happens when it opens. > > Exactly what I'm doing. Except no endoder, stepper driven and likely > needs a bigger motor, and more speed reduction to improve the holding > power. Thats a downright puny motor on it now, and I have a 270 oz/in > currently holding down a stepladder step. 8 wire so slower top speed > but easy on the psu. In fact I think I'll check and see if its shaft > is compatible yet today. It was, and its been installed. Not tested yet, I need a male GS-16-4 or 5 to hook up the home switch, AND send a signal back to hal that tells it its plugged in. I haven't figured out yet what to do with the signal though. But from what I can find on fleabay, it looks like I'll have to make a backshell and strain relief, the males I've found are all panel mount. Nothing but a 16mm panel nut for a back end. Sigh. I was born either 40 years early, or 40 years too late. I'd flip a quarter but it stands a measurable chance of not coming back down. :) > > So run the home switch circuit through the encoder connector and > > wire the mating encoder connector to have the connection closed. > > From the CNC controller perspective the system is already homed. > > Thats not how lcnc homes. In fact if the switch is closed, it jogs > away till it opens, THEN goes into the normal home search routine. I > use that to advantage on the Sheldon to assure it actually searches > for the switch closure. By sensing the front gib, which is NOW a > solid bar the width of the carriage, once it has approached the > spindle and closes, it stays closed, At homing, it will back away to > the right till it opens before the normal search begins. > > I found this undocumented behavior when I put home switches on TLM. > Putting in on the back of the bed because the screw is in the way on > the front, and set the switch roller to touch the tapered gib holders > bottom as it goes by. In fact I had to do a minor rebuild because I > added the gibs. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
