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Author Topic: C11gs BOB from CNC4PC 0-10vdc output, can't get below .517vdc at S0 speed  (Read 7970 times)

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My C11gs BoB is working great, controlling my VFD from Mach3.  The only problem is that MIDI command S0 causes the C11 D-A output to be .517vdc instead of 0vdc.  S24000 = 10.000 (adjusted by the trip pot on the BoB).  All intermediate speed commands scale between .517vdc and 10vdc. (ie, S12000 = 5.26vdc) My spindle Pulley 1 is set up to 0-24000 speed, ratio 1.  Everything works great except the pesky low end won't zero out at S0.  Arturo at CNC4PC says this is a Mach3 issue, involving PWM setting on the P&P Spindle page, and the Motor Tuning Step pulse width.  I change the PWM setting from 50 - 1000, nothing happens to the .517vdc @ S0.  I have tried pulse widths 1 - 5, with no effect on the .517vdc @ S0. 

Any enlightenment on this problem would be greatly appreciated!

Ozzie

Offline derek

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I have the same problem with the C32 as well. I think it's inherent to the design. I need near zero output for my ATC indexing. I ended up putting an old Homann controller on.

Derek
Thanks Derek, I think you're probably right.  I'm going to give Arturo another shout, but I don't think I'm going to be able to use his PWM solution.  First of all, I just can't live with 1200 RPM demand sitting there all the time....that's not safe.  And secondly, the spec says 0-10vdc, not .5-10vdc.  I love everything else about the C11gs.  I've been looking at the Homann DC05 I think it is.  The manual on his site isn't much better than the Chinese VFD manuals for content, and accuracy.  Kind of hard to follow the setup and testing, but at least from what I've read, the specs are solid.  That's what counts.  Besides, the Huanyang VFD,s can be set to ignore up to 10Hz starting demand which is about .25vdc on the 0-10vdc scaling.  That would be a nice solution, if Arturo could get it below that level.  I'll see.  I assume Homann's is already well below that, from what I've read.

Ozzie  
Just add in a 1K resistor in line. I have seen that one before.