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Problem: AC servo motor

Open rewwer56 opened this issue 6 months ago • 10 comments

Wiki Search Terms

RS485, AC SERVO MOTOR,

Controller Board

6-pack, original fluidnc board

Machine Description

Lathe. Nema34 steppers as x and z axis. AC SERVO motor with controller as spindle

Input Circuits


Configuration file

Not applicable

Startup Messages

Not applicable

User Interface Software

Webui

What happened?

Cannot get the servo motor controller to communicate with fluidnc board. Manual rpm input on motor controller to motor is working. Only not from fluidnc board

GCode File

Not applicable

Other Information

No response

rewwer56 avatar Jun 18 '25 18:06 rewwer56

We need datasheets on your parts and a schematic of how you are hooking everything up.

The config file and messages are applicable. Please edit your initial post to add them.

If you are trying to use RS485, we do not support that.

http://wiki.fluidnc.com/en/hardware/motors/servos

bdring avatar Jun 18 '25 18:06 bdring

What type of communication between the two controllers do you suggest?

rewwer56 avatar Jun 18 '25 18:06 rewwer56

Image

bdring avatar Jun 18 '25 18:06 bdring

Thanks

rewwer56 avatar Jun 18 '25 18:06 rewwer56

I just want to clarify something. The thing about supporting only step/direction control applies to axis motion, not to spindle control. For spindles, we support the following control methods:

  • Manual operation
  • On/off via digital signals, relays or solid state relays
  • Direction via digital signals or relays
  • Speed control via 0-10V analog or digital PWM
  • RS485 communication using the Modbus protocol

As Bart said, we would need more information about the controller for your servo motor to know if it is compatible with the above methods.

MitchBradley avatar Jun 18 '25 18:06 MitchBradley

Many of the AC Servo controllers that I looked at support Modbus RTU communication, for use with, for example, PLCs. FluidNC supports Modbus RTU. We have "out-of-the-box" support for the specific Modbus messages that are used by a few particular VFD models, but it is unlikely that any given AC Servo controller uses exactly the same messages. We have a "generic VFD" module that can be configured with custom message formats. It is possible that, if you can find documentation about the message details for your particular controller, the generic VFD module would work with it.

MitchBradley avatar Jun 18 '25 19:06 MitchBradley

Good day,

I've this servo-set: https://www.omc-stepperonline.com/a6-series-750w-rs485-ac-servo-motor-kit-3000rpm-2-39nm-17-bit-absolute-encoder-ip67-a6-rs750h2a1-m17

rewwer56 avatar Jun 19 '25 18:06 rewwer56

It looks like it should be possible to control that with RS485, but the download link for the manual is broken so I can't be sure. When I tried to download the manual for the servo drive, I got "ERROR 403: Forbidden."

MitchBradley avatar Jun 19 '25 18:06 MitchBradley

Based on page 27, I think you need to turn it on with a digital signal via S-ON and control the speed with a 0-10V output via A11._

MitchBradley avatar Jun 20 '25 04:06 MitchBradley