On Thursday 28 May 2015 08:59:12 [email protected] wrote: > On Thu, 28 May 2015, andy pugh wrote: > > On 28 May 2015 at 00:40, <[email protected]> wrote: > >>> When you connect the mains supply, does 5V appear on the pin shown > >>> in orange in that picture? > >> > >> No, I get about 0.25 volts > > > > 0.25 volts relative to where? > > In the 4th picture between the 4th and 5th terminal from the left > marked 5v and gnd > > > I guess relative to the PWM pin would be > > the right place to measure. > > > > Anyway, if that is what you measured it means it is probably an > > input to an opto-isolator, so you can connect 5V from the BoB to the > > 5V and the PWM pin from LinuxCNC to the PWM pin. Invert the PWM > > output so that 100% PWM is 0V on the pin and 0% PWM is 5V on the pin > > and it might work. > > > > -- > > atp > > If you can't fix it, you don't own it. > > http://www.ifixit.com/Manifesto
I think this is a place where I would query the seller for instructions in a language you understand. I would make the comment that the "control" connections are probably hotter that a 3 dollar bill when line power is applied and switched on. Meaning that the driver you use must be completely opto-isolated. Most any of the pwm convertors sold by numerous vendors will conform to that. The Mesanet "spin X1" is quite linear, as is the PMDX-107 if its like the PMDX-106 I've used for years on my toy mill. ANY connection between those terminals and a real ground will let out all the smoke & break the mirror & it doesn't work anymore. So the driver circuitry MUST be totally opto-isolated. Some aftermarket boards can supply the +10 volts using the 0 volt terminal as ground reference, and some try but fail so you dont get the full 10 volts of control range. I have modified the cnc4pc board to get that 10 volts, but its conversion linearity isn't at all linear. The Spin-X1's conversion linearity is quite good, 1% accuracy rated. Conversion linearity, even for an excellent interface, becomes quite non-linear if the control point in this amplifier/driver, is not well buffered from the amplifiers error summing point, in which case a 10k to 50k resistor in series with the variable voltage the interface generates, will go a long ways toward correcting the non-linearity into something that a hal module called lincurve can correct for you if you need that 1%. I usually have feedback from the encoder back into the PID, which usually brings that a lot closer to the proper control. The endcoder, with its index at once per turn make you accurate enough to do rigid tapping, but that motor hasn't got the twist to do that at the rpms used for tapping. Based on that factor, I wouldn't bother with an ABZ encoder, but would rig a 1 pulse per rev as a speed feedback, used in the hal file for both feedback to the PID controller, and for an instant stall detector. The way I have my lathe setup, motion is disabled when the near module says the motor is loaded & the rpms are sagging. I can peck tap on the lathe and haven't broken a tap yet. I have tore up the drive belt & timeing pulley entirely too often, but thats a different problem currently being designed around. 7x12's were never intended to do peck tapping. 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
