On Apr 8, 2012, at 5:43 PM, Peter C. Wallace wrote: > On Sun, 8 Apr 2012, Jeshua Lacock wrote: > >> Date: Sun, 8 Apr 2012 15:14:15 -0600 >> From: Jeshua Lacock <jes...@3dtopo.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] Mesa counter card? >> >> > >> Can anyone tell me how I would wire up the encoders? Are they connected >> through the parallel cable, or some other way? >> >> If anyone from Mesa is listening, can you provide a crude diagram? I am a >> visual learner, so that would be most appreciated. > > TTl (single ended) Encoders can be connected to the bare FPGA pins. Normally > encoders have 3 pins each: A,B and I (or Z) so if for example a 5I25 FPGA > configuration had encoder 0 connected to parallel port pins 1,2, and 3 you > might wire encoder0-A to parallel port pin 1, encoder0-B to parallel port pin > 2 and encoder0-Z to parallel port pin 3. (if you dont have or need the > index/Z > pin it can be dropped)
Hi Peter, Thanks for your response. I am currently using TTI encoders with just A and B, so that all sounds fine. > There is a risk with direct connection of these signals that the FPGA card > could be damaged if either ESD or excessive voltages were applied > accidentally > to the I/O pins (This also applies to standard parallel ports). The 5I25 is > safe for inputs from -.6V to +7V. If a voltage beyond this range is applied > to > the FPGA pins, the 5I25 will likely be damaged. For this reason we supply > breakout boards that are more rugged. Also for high speed and noise immunity, > differential encoder signals are preferred to single ended signals. These > differential signals are also supported by our breakout cards. I am currently powering my encoders from the 5V from my computers USB port, so I guess something really terrible would have to happen to exceed 5V. That said, what break out board would you recommend? I may go with differential signals some day, but I have not had any issues with noise thus far. > All that said, for simple step/dir + TTl encoder use, you can get away > without > any breakout card. For example the G540 configuration is pinned out to > connect > directly to a G540 multi axis step drive. This in no way means it would only > work with a G540, just that its pinout matches the G540 so no special > cable/adapters are needed to connect the 5I25s DB25 connector to the G540s > DB25 connector. If you wanted to use the step/dir outputs of a G540 > configuration on individual step drives you would just need to check the > G540 FPGA pinout and wire the "parallel port pins" accordingly. That is, > there > is nothing G540 specific about the configuration except its pinout. So all I have to do is provide you with a list of my pinouts and I am basically set after I rewire the wires from the encoders from the Geckos to the correct pins? Do you have any guides or offer assistance with configuring EMC? > If you have an existing parallel port pinout with encoders and step/dir, this > can easliy be duplicated in a custom 5I25 configuration. This probably sounds > more exotic than it really is, as only a single pinout definition file needs > to change to generate a new configuration, basically a 5 minute cut/paste > edit > job and a re-compile. Sounds perfect. Thanks again, Jeshua Lacock Founder/Engineer 3DTOPO Incorporated <http://3DTOPO.com> Phone: 208.462.4171 ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
