forum.cncdrive.com

Hi,

I had some break with my CNC project and wanted to push it forward - but my Servos are not moving. At some point, I tested it shortly wiring to the board and the servo was working. Now I just cannot get it to move.

I am using 300ETH with Breakoutboard (big one).

Servos get the power 48V and just make pulsing noises, but no matter how I wire it they just dont move. I tried to wire PNP and NPN way, no success. I tried different pins in the breakout board. I tried also to use different ports in the UCCNC 300ETH. Could I damage the board somehow? Please give me some ideas where should I look for error... Do I miss something obvious...?

I have oscilloscope, multimeter.

A wiring diagram of the Servo Drive itself AND a diagram of how you have wired it to your board would help with diagnosis.

true. forgot to include:

this is one option which I tried:


this is second option which I tried:


in both cases no success.

I made today also the following test: I removed the PCBS from the control box and made a test circuit using only UCCNC300ETH and BREAKOUT BOARD without anything else connected to it (apart from Powersupplies). I connected the oscilloscope to the output 1 (which should be PUL signal) / here are the results (which look suspicious to me):

this is how that looks with ACTIVE LOW option:


this is how that looks with ACTIVE LOW deactivated:


any ideas?

kucharzb wrote:true. forgot to include:

this is one option which I tried:

fenjaV1.jpg

this is second option which I tried:

fenjaV2.jpg

in both cases no success.

I made today also the following test: I removed the PCBS from the control box and made a test circuit using only UCCNC300ETH and BREAKOUT BOARD without anything else connected to it (apart from Powersupplies). I connected the oscilloscope to the output 1 (which should be PUL signal) / here are the results (which look suspicious to me):

this is how that looks with ACTIVE LOW option:

image_50416129 (12.JPG

this is how that looks with ACTIVE LOW deactivated:

image_50439169 (12.JPG

any ideas?

That will not work.
The UC300eth needs it's OWN 5V power supply. The ucbb will not supply it like that.
You will be getting nothing from the uc300!!!.

OK / i connected the UC300ETH to the powerbank and disconnected the 5V supply coming from the breakout board.

It changed nothing. It looks on the oscilloscope exaclty the same, so this is not the case....

for me suspicious is not only the shape of the signals, but also the voltage / which in "positive" mode should be rather like 5V, not 0,7? or am I wrong?

If you measuring voltage on the UCBB outputs with nothing connected to it, that will give you about 0volts measurement always.
This is because the UCBB has NPN open collector outputs, so it cannot source current, it can only sink.
To measure it add a resistor between the output and a positive voltage, e.g 5v or 24v and then measure the output signal.

OK, I put a 50Ohm resistor between O1 and 5V and the results are different!

Here is with active low activated:


Here is with active low deactivated:


Thank you very much for pointing this out! I must have somehow missed that...

Now questions:
1) after connecting Servo / should I leave that resistor between O1 and 5V
and
2) Should the same be done with O2 (dir signal)?

in the manual there are no resistors when using 5V line.

I think you should read after how NPN open collector outputs work, because it seems to me that you do not understand it.
Ofcourse no resistor is needed when the servo's optocouple is connected to the output, because then the current flows from the positive voltage source +5V, +12, +24V or whatever through the optocoupler through the NPN output to ground.

cncdrive wrote:I think you should read after how NPN open collector outputs work, because it seems to me that you do not understand it.

thank you for kind words, you are right I will read about it.

cncdrive wrote:Ofcourse no resistor is needed when the servo's optocouple is connected to the output, because then the current flows from the positive voltage source +5V, +12, +24V or whatever through the optocoupler through the NPN output to ground.

thats what thought. but then... why it doesnt work? I will make today another test with motor connected. I have really no ideas... especially that it already worked at some stage before...

OK - something is not right I think...

This is what STEP signal looks like after connecting servo...


With DIR is even worse, since I can't even measure it with oscilloscope - something changes when I move the axis, but it is so low that it is on the level of noise floor...

What could that suggest?