Ohms law is your friend here. V=I x R where R is Ohms, I is Amps and V is volts.
And P = V x I where P is watts, V = voltage and I is Amps. So substitute I x R for V and you get P = I^2 x R Or I = V/R and you get P = (V^2)/R John > -----Original Message----- > From: andrew beck [mailto:andrewbeck0...@gmail.com] > Sent: March-30-20 8:30 PM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] connecting up mpg > > that sounds easy enough thanks john > I will measure it now. I have a 5v fanuc mpg also now but am not that keen > to use it as it is pretty rough and will be a pain to turn > > On Tue, Mar 31, 2020 at 4:03 PM John Dammeyer <jo...@autoartisans.com> > wrote: > > > Take a 12V power supply and measure the current drawn by the encoder at > > 12V. Say it's 100mA. That's 1.2W from I * V. You want to drop 12V from > > the 24V supply. > > > > 12V / 0.1A is 120 Ohms but it should probably be about 2W or better. If > > all you have are 1/2W resistors then four 470 ohm (standard value) in > > parallel is 117 Ohms. Or some 510 Ohm or a mix in parallel. > > > > But measure the encoder while you are turning it just in case it draws > > more at one position than another. > > > > John Dammeyer > > > > > -----Original Message----- > > > From: andrew beck [mailto:andrewbeck0...@gmail.com] > > > Sent: March-30-20 7:40 PM > > > To: Enhanced Machine Controller (EMC) > > > Subject: Re: [Emc-users] connecting up mpg > > > > > > hey guys I love both the suggestions. I have a problem though. > > > > > > the whole of New Zealand is currently on lockdown and I can't buy > > anything. > > > > > > I have a whole box of resistors that I bought and might have a few diodes > > > left. > > > > > > is it possible to hack something together for now? > > > > > > and also do you guys think it would be possible to connect 24 volts > > > directly to the 12 volt mpg or I am going to blow something? my initial > > > thought it bad idea but it can't hurt to ask > > > > > > On Tue, Mar 31, 2020 at 3:36 PM Chris Albertson < > > albertson.ch...@gmail.com> > > > wrote: > > > > > > > How much current is needed in the 12 volt supply? I'm guessing less > > > > than 100 ma. > > > > > > > > If you have 24 volts DC available then you can drop it down to 12 > > volts a > > > > few different ways but the simplest might be an LM7812 linear > > regulator. > > > > The LM7812 is nearly bomb proof. These cost under $2 > > > > Look at figure 9 on the datasheet and note the values of the caps are > > not > > > > critical at all. > > https://www.mouser.com/datasheet/2/149/LM7812-461970.pdf > > > > <https://www.mouser.com/datasheet/2/149/LM7812-461970.pdf> > > > > > > > > > > > > > > > > On Mon, Mar 30, 2020 at 6:54 PM andrew beck <andrewbeck0...@gmail.com> > > > > wrote: > > > > > > > > > hey guys I was asking about connecting a 12v mpg encoder to my mesa > > 7i76 > > > > > card. last week. I have done some testing with a pc atx power supply > > > > and a > > > > > multimeter and it looks like at 12 v when measuring between the A > > channel > > > > > and ground(0V) the high value is 5.2 volts and low is zero(or close > > to > > > > it) > > > > > also there are some nice status leds that show what the channels on > > the > > > > mpg > > > > > are doing. > > > > > > > > > > when powering it with 5 volts the leds don't work and the high > > voltage is > > > > > 2.7 volts and the low is zero volts. I read the threshold in the mpg > > > > > inputs is 2.5 volts with 10 percent hysteresis so I need to pull at > > least > > > > > 2.8 volts. also I am thinking that might be a bit close and result > > is > > > > > unreliable operation. > > > > > > > > > > Is there anyway I can supply this with 12 volts from my board? I am > > > > > running the field voltage at 24volts. > > > > > > > > > > regards > > > > > > > > > > Andrew > > > > > > > > > > > > > > > On Tue, Mar 24, 2020 at 7:53 AM Peter C. Wallace <p...@mesanet.com> > > > > wrote: > > > > > > > > > > > On Tue, 24 Mar 2020, andrew beck wrote: > > > > > > > > > > > > > Date: Tue, 24 Mar 2020 07:34:01 +1300 > > > > > > > From: andrew beck <andrewbeck0...@gmail.com> > > > > > > > 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] connecting up mpg > > > > > > > > > > > > > > Hey Peter. > > > > > > > > > > > > > > When I enable the mpg mode does that mean I will lose my whole > > config > > > > > or > > > > > > do > > > > > > > I just need to change something in the Hal file. > > > > > > > > > > > > YOU just change some settings in the hal file > > > > > > > > > > > > > > I'm thinking It sounds like the best thing is to setup all my io > > in > > > > > > > pnfconfig leaving the mpg inputs spare and then after that start > > hard > > > > > > > coding in Hal. > > > > > > > > > > > > Yes leave the 2 or 4 pins (for 1 or 2 MPGs) free if you want to > > use a > > > > MPG > > > > > > Note the enabling the MPG in the hal file will not cause you to > > lose > > > > the > > > > > > ability > > > > > > to use inputs 16..19 for normal digital input use > > > > > > > > > > > > > Do you know how much I can do in pnfconfig? > > > > > > > > > > > > > > > > > > > I dont think pncconf supports MPG setup, so this needs to be done > > by > > > > > > editing the > > > > > > HAL file > > > > > > > > > > > > > > > > > > > New Zealand is going in to total isolation for a month from > > tomorrow > > > > > > > because of covid 19 so I have some time for this lol :) > > > > > > > > > > > > > > Regards > > > > > > > > > > > > > > Andrew > > > > > > > > > > > > > > Regards > > > > > > > > > > > > > > Andrew > > > > > > > > > > > > > > On Mar 24, 2020 3:18 AM, "Peter C. Wallace" <p...@mesanet.com> > > wrote: > > > > > > > > > > > > > > On Mon, 23 Mar 2020, andrew beck wrote: > > > > > > > > > > > > > >> Date: Mon, 23 Mar 2020 17:32:56 +1300 > > > > > > >> From: andrew beck <andrewbeck0...@gmail.com> > > > > > > >> Reply-To: "Enhanced Machine Controller (EMC)" > > > > > > >> <emc-users@lists.sourceforge.net> > > > > > > >> To: "Enhanced Machine Controller (EMC)" < > > > > > > emc-users@lists.sourceforge.net> > > > > > > >> Subject: [Emc-users] connecting up mpg > > > > > > > > > > > > > >> > > > > > > >> Hey guys. > > > > > > >> > > > > > > >> I have a 12 volt mpg > > > > > > >> > > > > > > >> I want to connect it to the 7i76 board. do you know if I can > > > > connect > > > > > it > > > > > > >> straight up. I think that the mesa boards only want 5 v and I > > am > > > > not > > > > > > sure > > > > > > >> how to connect up my 12 volt mpg > > > > > > >> > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > https://drive.google.com/file/d/1uOF2y7KFSchXLhQ3s79GSB1x_WZieQ5l/view?usp=sharing > > > > > > >> > > > > > > >> I did a bunch of searches on the forum but couldn't get a > > definite > > > > > > answer. > > > > > > >> > > > > > > >> I tried to attach a photo but it bounced back. so here is a > > link > > > > > > >> > > > > > > >> regards > > > > > > > > > > > > > > > > > > > > > You can connect a 12V MPG to the 7I76 MPG inputs (field inputs > > > > 16..19), > > > > > > but > > > > > > > not > > > > > > > the high speed encoder input. Note that the input threshold for > > MPG > > > > > > inputs > > > > > > > is > > > > > > > 2.5V so the MPG output needs to swing close to ground for > > reliable > > > > > > operation > > > > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > >> < > > > > > > > > > > > > > > > > > > > > > > > > https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail > > > > > > >> > > > > > > >> Virus-free. > > > > > > >> www.avast.com > > > > > > >> < > > > > > > > > > > > > > > > > > > > > > > > > https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail > > > > > > >> > > > > > > >> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> > > > > > > >> > > > > > > >> _______________________________________________ > > > > > > >> Emc-users mailing list > > > > > > >> Emc-users@lists.sourceforge.net > > > > > > >> https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > >> > > > > > > > > > > > > > > Peter Wallace > > > > > > > Mesa Electronics > > > > > > > > > > > > > > (\__/) > > > > > > > (='.'=) This is Bunny. Copy and paste bunny into your > > > > > > > (")_(") signature to help him gain world domination. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > > Emc-users mailing list > > > > > > > Emc-users@lists.sourceforge.net > > > > > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > > > > > > > _______________________________________________ > > > > > > > Emc-users mailing list > > > > > > > Emc-users@lists.sourceforge.net > > > > > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > > > > > > > > > > > > Peter Wallace > > > > > > Mesa Electronics > > > > > > > > > > > > (\__/) > > > > > > (='.'=) This is Bunny. Copy and paste bunny into your > > > > > > (")_(") signature to help him gain world domination. > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > Emc-users mailing list > > > > > > Emc-users@lists.sourceforge.net > > > > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > > > > > > > > > _______________________________________________ > > > > > Emc-users mailing list > > > > > Emc-users@lists.sourceforge.net > > > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > > > > > > > > > > -- > > > > > > > > Chris Albertson > > > > Redondo Beach, California > > > > > > > > _______________________________________________ > > > > Emc-users mailing list > > > > Emc-users@lists.sourceforge.net > > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
