# G76 problem

17 Dec 2022 23:32 #259779 by andypugh
Replied by andypugh on topic G76 problem

how is it possible to lose steps with a closed loop motor?

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It certainly should notice...

Maybe your step timings (step and space) are a bit marginal but this is not noticed at low speeds (this might be linked to the step polarity not being what you think. Does the step pin connect to the top or the bottom of the drive input optocoupler? )
The following user(s) said Thank You: Ismacr63

17 Dec 2022 23:39 #259782 by Ismacr63
Replied by Ismacr63 on topic G76 problem

andypugh publicación = 259779 ID de usuario = 723

Ismacr63 publicación = 259778 ID de usuario = 33444
¿Cómo es posible perder pasos con un motor de circuito cerrado?

Sin duda debería notarlo...

Tal vez los tiempos de paso (paso y espacio) son un poco marginales, pero esto no se nota a bajas velocidades (esto podría estar relacionado con la polaridad del paso que no es lo que piensas. ¿El pin del paso se conecta al superior o inferior del optoacoplador de entrada del variador?)

Forgive me but I get a little lost with what you tell me.

17 Dec 2022 23:43 #259784 by andypugh
Replied by andypugh on topic G76 problem
Do you have a circuit diagram for the stepper drive control pins?

17 Dec 2022 23:52 #259786 by Ismacr63
Replied by Ismacr63 on topic G76 problem

Do you have a circuit diagram for the stepper drive control pins?

I used this diagram that I found on the net.
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17 Dec 2022 23:56 #259788 by andypugh
Replied by andypugh on topic G76 problem
That's the BoB, not the stepper drive.

18 Dec 2022 00:03 #259789 by Ismacr63
Replied by Ismacr63 on topic G76 problem

That's the BoB, not the
step​per drive.

are you referring to this?
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18 Dec 2022 00:22 #259790 by andypugh
Replied by andypugh on topic G76 problem
Yes. That indicates that the drives use differential inputs, so as long as you have 7i76 step + to drive step + (and so on) then it isn't a step polarity issue.

18 Dec 2022 07:02 #259801 by JPL
Replied by JPL on topic G76 problem
I've found another manual for the T60 drive here: www.rtelligent.net/upload/wenjian/Steppe...%20User%20Manual.pdf

I think you should have a look at sect 4.5 related to SW8.
In your manual it is for the bandwidth selection but in the manual linked above it is for Open/Closed loop selection, According to the pdf manual (above) SW8 should be set to 'off' for closed loop mode.

This is quite strange since just about everything else is identical in both manuals.

18 Dec 2022 07:53 #259803 by Ismacr63
Replied by Ismacr63 on topic G76 problem

I've found another manual for the T60 drive here: www.rtelligent.net/upload/wenjian/Steppe...%20User%20Manual.pdf

I think you should have a look at sect 4.5 related to SW8.
In your manual it is for the bandwidth selection but in the manual linked above it is for Open/Closed loop selection, According to the pdf manual (above) SW8 should be set to 'off' for closed loop mode.

This is quite strange since just about everything else is identical in both manuals.

Yes, a few posts back I put an image that shows that sw8 off is for servo, it's just how I have it. Before, I used mach3 with more speed than in linuxcnc and I didn't have problems of losing steps.