Hi Gene, > > > Yes, that encoder will run out of bandwidth trying to get thru that > > > bobs opto-iso circuitry. So you are out the cost of at least a 5i25 > > > which has at least 100x more bandwidth at its encoder inputs. I've > > > had to cut and bypass the opto crap on the bobs several times now. I > > > am a CET, but many machinists far more capable than I at turning > > > cranks, wouldn't feel comfortable doing such hacking. > > > > Actually not a problem. Especially for the spindle. > > Thats 10k edges per rev, and 3000 revs, that 300,000 edges a second, and > right at or slightly beyond the bandwidth you can shove thru an > opto-isolater. Expect problems John.
Not really. 3000 RPM is 50 RPS. With 50 revs per second * 10,000 edges per rev is 500K edges per second. Although the Bergerda drive, using single ended opto is, spec'd to only 200Khz pulse rate the RS422 input format is good to 1Mhz. I've already made the motor turn at 3000 RPM using my Agilent programmable waveform generator set to a output 5V waveform with 1uS wide pulses and 500kHz. And if I set up the pulse multiplier I can reduce that. The PMDX-126 doesn't have opto for the step/dir outputs because they feel most drivers out there already have that. And there are lots of opto's out there now that are more than fast enough. Single-Channel: 6N137, HCPL-2601, HCPL-2611 Dual-Channel: HCPL-2630, HCPL-2631 High Speed-10 MBit/s Logic Gate Optocouplers > > Here on the g0704, I have a 1000 line encoder on the rear of that 1hp 90 > volt motor. At 1500 spindle revs, the multiplier is just above > 14000/rev, so the input to the encoder is coming in at 21,750,000. Its > been run thru a couple rs-485 convertors, but the 5i25 is not haveing > problems with it. Which amazes the heck out of me. But mama says shes > hungry, and see that famous sign. Back eventually. A 1000 line encoder is 4000 edges per rev in quadrature but each of the A and B are still only 1000 pulses /second. At 25 RPS, (1500RPM/60) that's only or 25kHz. Not really all that high. All depends on how the hardware handles the two phased signals. John _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
