clunks / missing steps - DM856 and single pulse operation

[FatFreddie]

Why is that? what I meant to say is that eventually it all comes down to the same 230VAC connection, so ground on both should be at the same potential. Or am I missing something obvious?

It doesn't quite work like that, it's sort of complicated depending on earthing arrangements etc but you definitely need the DC grounds (maybe a bad term - DC 0v is better) connected.

[EddyCurrent]

Well I was surprised because it looks like you know what your about but it may be I'm at cross purposes.
I'm on about this.


But I then realised you might be saying this;

"I'm using the same power supplies for both the DM856 and the HBS86 tests"

[Jonathan]

Since the drive inputs are optically isolated, you shouldn't connect the PIC DC ground to the driver supply DC ground as that looses isolation. I think there could easily be enough noise on the driver DC ground to cause incorrect signals on the inputs if you tied them together.

What you're trying to do should take about 5 minutes, not days, so there's probably something simple we're missing. Could you carefully draw out the complete schematic of what you've set up?

On the 7805 I have 9VDC on the input and 5.01VDC on the output.

I'm pretty sure Irving was asking to find what capacitors (if any) you'd put on the input and output of the 7805. The datasheets give typical values, which should be fine for this.

The 'clunking' you describe is normal at low speed, since the motor stops after every step. At high speeds a good driver will run the motor in a different way with continuous angular speed, so you wont hear the steps.

[dsc]

Ok then, here's a connection diagram:



I'm using this as power supply:

Solderless MB-102 Breadboard Power Supply - Dual 5V and 3.3V DC Jack and USB New | eBay

As it can be used on a breadboard, had enough faffing about with 7805 on their own (too thick legs to fit on a breadboard). Not sure about what capacitors it's using, as it's all tiny SMD stuff.

I'm using the SPS705 unregulated power supply from Leadshine (Zapp) and used it on both the DM856 and the HBS86.

The only other thing is the setting on the DIP switches for the current, I was told by Zapp to set it to 2.1A peak, currently it's software configurable, but I can't connect to the driver as the software package from Leadshines drops the RS232 connection for some reason when I view the config of the driver.

Regards,
T.

[Jonathan]

What you've drawn look fine to me.
Have you put a decoupling capacitor adjacent to the PIC? e.g. 0.1uF capacitor across VSS and VDD.

[irving2008]

Jonathan got the point of my questions exactly right. The driver ground and the PIC ground should be kept separate.

That power board is fine for a PIC assuming you have nothing else loading it; it's good for 700mA and has the required decoupling. Do you have any decoupling capacitor (100nF typically) on the PIC power pins? Shouldn't really be necessary on a breadboard that size (I'm assuming the PIC is on the breadboard) but sometimes not having one can cause oddities.

Otherwise I can't obviously see where you're going wrong.

[EddyCurrent]

I think I had in mind source connections

[dsc]

Just confirmed I do have a decoupling capacitor between VSS and VDD on the PIC (right next to the PIC), value 100nF (104 code on the ceramic capacitor).

I changed the DIP switch setup, setting the peak current to 2.1A and done autotune via SW4 (toggled ON / OFF within 1sec, could hear some variable buzzing from the driver afterwards, I'm guessing it was the autotune process):



Tested the whole thing again and no luck, the motor simply goes a few steps, then vibrates without moving after I press the tactile switch, then moves slightly after a second press and then jumps on the third press. I've tried it with a PWM output and that seems to work without any issues. I'm lost as to what's wrong, especially since it works with the big Nema 34 motor and the HBS86.

Just to double check the wiring, here's the connections to the motor:



A+ BLACK
A- GREEN
B+ RED
B- BLUE

This comes from a spec sheet for the motor itself.

Regards,
T.

[dsc]

Did some further testing today with a signal generator. It was wired as a source rather than sink, but I could easily repeat the glitches and sudden jumps by changing the frequency of the pulse signal (say from 1Hz to 2Hz). This is similar to generating pulses via tactile switch and seems consistent with what I've seen before. Constant pulse generation (similar to hold the tactile switch) from the pulse generator shows a pretty smooth action.

I think I've tried everything I could and I'm waiting for a reply from Leadshine.

Regards,
T.

[dsc]

Based on the testing done by Gary, these DM856s all struggle with low frequency pulses / single pulse operation.

Can anyone recommend a driver which can handle 68VDC and drive a SY57STH56-2004A motor:



?

Regards,
dsc.