g203v steppers "jump" when system e-stops

[urbanimports02]

i have a novakon mill with cnc4pc c11g BoB and g203v drives running nema 34 1840oz steppers, and have had a problem that is getting worse as time goes, and finally nailed it down to an estop problem. i have always noticed an audible bonk noise when estop is activated and have been told it is normal, but recently it is getting so loud and severe that it shakes the floor. i have been suffering lost position and finally realized that the steppers actually move when estoped. if you hit it repeatedly, the lost steps add up, about .005" per instance. this is when sitting still, not estopping when in motion. the mill has a door latch safety switch, so every time you do a tool change, it estops, and you have to reset when the tool change is done. this happens when clicking estop in mach3, hitting the button on the machine, unplugging the parallel cable between pc and BoB, removing 5v from c11g EN pin, anything that disables the outputs for step and direction. it happens on all three axis, not just one bum drive. any thoughts?

[john_100]

I don't use either the C11 bob or Gecko G203 driver

but I expect the bob output normally is at logic 0 ,
pulling the G203 step input to 0v so the drives step optoisolator LED is on

step pulses go from logic 0 to logic 1 and after a delay back to logic 0
the drive stepping on the positive going transition

when you operate the E stop the bobs output goes either to logic 1 or
high impedance and this is seen by the G203 as a positive going transition and
steps

John

update ----- now I've searched for the Gecko manual
the opto isolators cathodes are commoned not the anodes as I assumed
and may change have the logic levels when the E Stop is opperated, but not the affect to the G203's step input

have you used the G203's enable input on terminal 7 ??

if you have not , using the E stop circuit to disable the Gecko drives could be the answer

[urbanimports02]

well i seemed to have fixed it after 2 years of running the machine, the dir low active was checked in mach3 ports and pins motor outputs. i unchecked them, and now all is silent when hitting and resetting estop, and the axis still move very smooth, maybe more smoothly then before. when i got my machine, the xml file would not run it, and novakon is not known for good support, or really knowing what they are doing at all. you ask questions, and they rarely have answers. khai the sales manager is very good, and makes them appear to have good service, but he is not a tech guy, so doesnt help much when you have a problem. anyway, i had set out to fix the xml to get my machine running, and never played with those particular settings. the other day, i played with setting the step to low active, which 2 axis already were, so i set the x axis to low acitve and reversed that axis in homing and limits, and it seemed to do the same thing. just now i unchecked both step low active and dir low active, and it seems to work great. step low active does not seem to fix my problem, so i would just like to have that setting correct. so what should the step setting be? low active checked or unchecked? i will go read the mach setup instructions to see if it makes sense to me. i see the gecko steps on the "1" logic, which is +5v on my BoB, just not sure what that means in terms of what mach is asking for. i know where that section is in the setup manual, so i will go have a read. i am learning more about this side of the system then i ever wanted to, which is good, since i just purchased a new novakon yesterday (clearance pricing was too tempting)

[john_100]

thats great you have it working OK

as for selecting active high or active low in Mach 3

it depends on which end of the drives optoisolator's LED is connected to the breakout board output

the LED will be on if either
the anode is connected to a positive supply via a resistor and the B.O.B 's output grounds the cathode

or the cathode is grounded (at 0 volts) and the anode is connected via a resistor to the B.O.B output at a logic 1 (+5V )

for the direction signal , if you select active low instead of active high
the motor will turn in the wrong direction

but if you made the wrong selection for the step signal
instead of stepping at the start of the narrow step pulse
it would step at the end of the pulse

normally the narrow step pulse is a fixed duration and the time between pulses changes with the motor speed

with active low selected instead of active high or vise versa
you have in effect a broad step pulse that changes width with speed
and a fixed , narrow gap between step pulses !

while some stepper motor drivers will work to a degree other will not

John