On Tuesday, 19 April 2022 12:46:20 EDT Peter C. Wallace wrote: > On Tue, 19 Apr 2022, gene heskett wrote: > > Date: Tue, 19 Apr 2022 12:24:26 -0400 > > From: gene heskett <ghesk...@shentel.net> > > Reply-To: "Enhanced Machine Controller (EMC)" > > > > <emc-users@lists.sourceforge.net> > > > > To: "Enhanced Machine Controller (EMC)" > > <emc-users@lists.sourceforge.net> Subject: Re: [Emc-users] nother Q > > for Peter > > > > On Tuesday, 19 April 2022 07:59:12 EDT andy pugh wrote: > > On Tue, 19 Apr 2022 at 03:51, gene heskett <ghesk...@shentel.net> > > wrote: > > > So by default. a bit is .142578125 volts. Hummm. Seems odd. I > > > would > > > have expected $00 to $FF as output. > > > > It does on the FPGA and the interface, but the driver converts to > > floating point for convenience and then the default scaling is to > > volts. > > > >Can I access it raw as the hex value? volts doesn't really represent > >what I need to work with. Although I assume the fp in volts does > >increment by the value of 1 bit change, so that can be worked around. > > You can scale as you wish with the scalemax parameter > > >How would I go about determining the resistor value to feed that input > >from nominally 42.3 volts to just bring it to full scale? My > >additional connections would "sink" it from there. > > You would need about 3K to get 36V into the 20K input impedance with a > 42V source > Ouch. That is going to need a power transistor on a heat sink to pull that down to 4 volts. Thats around 15 mils. And a 1 Watt R.
> >I have a small voltage applied to that input, but a halmeter is only > >reading a flicker of random noise at about 1 second intervals, zero > >the rest of the time. Thats likely a clue I'm doing something wrong, > >but what? > > Is the input relative to field power ground? (the field I/O section > section is galvanically isolated from the 5V parts of the 7I76) I'll have to check that. I thought it was. Did, According to my ohmmeter, it is a common ground. > > > I did get the flood button to appear in the axis gui, which is what I > will use to enable the mister air seperately from the mister pump, and > will interlock the pump so air has to be flowing before the pump can be > started. 'Twould be nice if I could relabel that radio button from > flood to air, can it be? > > >I did just find the pwmgen's pins, which despite the fact that they > >steal the 7i76's stepgen-4 pins, are addressed in the 5i25 as > >pwmgen.00.etc. No mention of that in the 7i76 docs I assume because > >the pwmgens are actually in the 5i25. Is pwmgen.01 then the same > >pins on the 5i25's p2? > You can use mesaflash to determine the 7I76 pins: Or as I found, enable the device in the loadrt line and read the cards signon output as you exec linuxcnc -l. However, pwmgen.00.'s outputs do show up on the DIR4+- and STEP4+-. terminals of the 7i76. But see 5i25man.pdf for data about it. > sudo mesaflash --device 5i25 --dbname1 7i76 --readhmid > > > (this needs mesaflash 3.4.2) Not available for buster, it has 3.4.0-rc1 or similar. Thank you Andy. 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, 1940) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
