AXBB-E analog output only from 1.2-10V instead 0-10V

[mr_cg]

Hello!

I have connected my spindle to analog output from AXBB-E controller.
Speed control in general is working properly but due to the fact that lowest possible analog output voltage is 1.2V the speed can only be controlled starting from about 3000 RPM up to 24000 RPM.

The analog ouput voltage range is not from 0V up to 10V as it should ... because the lowest possible value i could measure is starting from 1.2V.
Is there anything i can do in the UCCNC settings or some external electrical circuit?
The output voltage was measured directly on the controller and therefore i think it could be also design issue ... hopefully i am wrong.

Br
Chris

[mr_cg]

Something to add for solution finding.
The inverter allows to setup the lower limit of the voltage which corresponds to e.g. 0%.
But how to configure in UCCNC that e.g. S1 starts from 1.2V up to S24000 (10V)?
This would be potential solution but i do not know if and how this could be setup in UCCNC.
If this is not possible than this would be my feature request.

[Robertspark]

??

24000 / 10v X 1.2v

spindle speed min = 2880 rpm
spindle speed max = 24000 rpm


10v = pwm at 100%.... so that is your max own setting
therefore 1.2v set the min pwm at 12....

that should then ramp from 1.2 v 12% pwm to 100% pwm signal and from 2880rpm to 24000rpm..... just check that the min spindle speed can go so low..... as some of them start at 6000rpm as the torque
drops to not a lot

[cncdrive]

Did you measure it with the analog output not connected to anything?
If not then what is connected to it might pull too high current pulling the Voltage up.

No, it cannot be a design error. Furthermore our automatic tester circuit measures 256 Voltage points from 0 to 10V on the analog output of every boards.
The tester throws an error on 2% error at any point.
So, it is not possible that it gives 1.2V when it should output 0Volts, that would fail on the tests.

[Robertspark]

CNCdrive, is there a pwm frequency that works best for CNCdrive motion controllers to provide the best linearity.

the OP's screenshot has the pwm frequency set at 100hz in his screenshots, would this not be a bit course for the analogue output channel of the axbbe motion controller? should it be set higher?

[cncdrive]

Hi Rob,

The PWM frequency has no effect on the analog output. The PWM frequency effects only PWM outputs.

[Robertspark]

Hi Rob,

The PWM frequency has no effect on the analog output. The PWM frequency effects only PWM outputs.

thanks,

[mr_cg]

The issue was clearly caused by wrong design on my side.
Everythning ok on AXBB-E side.

Wrong wiring at the beginning (as it was shown in one YouTube video):

Code: Select all

INVERTER
#############################################
#     10V+     #     Sig     #     10V0     #
#############################################
        |             |              |
        |             |              |
       ###            |              |
       # #            |              |
       #R#            |              |
       # #            |              |
       ###            |              |
        |             |              |
        |_____________|              |
            |                        |
AXBB        |                        |
#############################################
#          AO1        #         5V0         #
#############################################

R=1.5kohm


Correct wiring (now analog spindle control works without issues):

Code: Select all

INVERTER
#############################################
#     10V+     #     Sig     #     10V0     #
#############################################
        |             |              |
        |             |              |
       ###            |              |
       # #            |              |
       #R#            |              |
       # #            |              |
       ###            |              |
        |             |     #####    |
        |_____________|_____# R #____|
            |               #####    |
AXBB        |                        |
#############################################
#          AO1        #         5V0         #
#############################################

R=1.5kohm


Thanks from my side for your help!

[cncdrive]

OK, good to hear that you found and fixed the problem.

[wattstar]

Just wondering where did you read to add a resistor? I couldn’t find anything about it in the instructions and I’m wondering if this is the reason my speeds are so far out (over 1000 rpm sometimes).