Re: Duet 3 use for other motion systems?

A brief update and a question
Update. I can control several motors well enough either singly or in coupled movement via the console.

Question: I need to be able to send Gcode from a PC, preferably python. From hints in the documentation and the CodeConsole, it seems like I should be able to use a simple POST to send a command and get the response. This is easy with the python requests library, a single line of code. I have a Duet3 and a raspberry pi on the network configured at the router with a static address. Here is the stupid simple code (due to my ignorance):

import requests

class Duet(object):
"""simple command post to duet"""

def __init__(self, URL = 'http://192.167.1.42/'):
    """stasch the URL
    check validity?
    """
    self.URL = URL

def DuetCmd(self, command):
    response = requests.post(self.URL, data=command)
    return response

DuetCmd times out. The default port is 80. Likely I have misinterpreted the use of the PORT on the Raspberry pi. So how does one send individual lines of Gcode to the pi, thence the Duet? Is there a simpler way to do this?
Many thanks for any suggestions or pointers to resources.

That must be interesting code. Will have to learn how to maintain such precision sync. Can I have two independent motion paths concurrently? 50 kHz time ticks is roughly what is needed, so that’s 20 microseconds. A 100 MHz ARM can execute 2000 instructions in that time, and given it’s RISC nature, it’s likely 10 or 20 instructions to do much of anything useful. Lots of time to run down a list of motors to step or some such. Using step and direction you could avoid the overhead of SPI.

How are the CAN bus expansion drives sync’d up to the main timer interrupt loop. An NTP like protocol can get you to sorta the 1 MHz CAN clock rate, a small fraction of the 20 us time slice. With oscillators good to 10^-6 you can wait a second before they drift apart by a microsecond. Or maybe get better oscillators but that gets expensive. VCO’s and tweak them on the fly? Or relax the sync requirement to 10 us.

Just ordered one, so the adventure begins. Maybe I just have to order one per multi-axis stage. They are so much cheaper than even Galil that that may be the easy solution.

Sorry to ramble. The questions are can I have multiple independent motion queues concurrently, started and stopped independently, and timing sync (or independence) across the CAN bus expansion units.

Thanks to all who have responded!

My (limited) understanding of the 5160 driver is that you can set a motion ‘profile’, with acceleration, max velocity, and deceleration all given via the SPI bus, and the chip does the necessary sequencing of the motor phases to achieve that position, velocity, acceleration (and jerk?) profile.

So the question then becomes, does processing a ‘command’, a line of g code, complete when the motor has been told what to do, and to ‘go’, or does it wait for an event, or status read back from the 5160 indicating the move is complete? For non-orthogonal printers, the relation between extruder tip position and motor position is quite complex. Yet I have to believe the extruder rate is kept reasonably proportional to the extruder velocity.

Most motor controllers, I think, let you update parameters in the middle of a move giving the Duet the ability to, for example, adjust the extrusion rate on the fly.

Such sophisticated parametric operation is likely(???) hidden from view by the printer setup commands (and subsequent adjustment of the movement and extruder profiles), but if the slicer has to handle such issues, then the implementation would seem to be at the g-code level, and thus commands must just kick off the movement, then process the next command so that the g-code can command the extruder dynamically.

I had hoped to avoid getting down into the weeds, and just define a configuration of a “printer” to be more like a robot arm.

@bearer
Yeah, I have been wondering about synchronization and multiple axes. But reading that the Duet can run so many different kinds of printers, I assumed it would permit simple configurations. Other motion control systems (Newport, Newmark , Parker) have explicit commands or techniques to synchronize motion, but single axis moves are always possible, independent of the activities of the other axis.
I wondered about the inverse problem. With the 5160 sophistication, how does the host ARM processor keep the axes coordinated? But that’s off topic.
Can’t I send a command to a single axis? Does the command interpreter force you to wait for one command to finish before starting the next one? Surely the movement of the extruder drive is independent of the head’s movement.
I clearly need to spend some quality time with the documentation.

Regards,
Jon

I have a number of projects that will need a stepper or two, mostly controlling positions of components on an optical bench. Rotating a filter wheel, turning fine thread screws or micrometers on stages to precisely control position or angle. Perhaps controlling the grating in a spectrometer. These will often involve reading instruments and adjusting position/angle, or a bit of simple image processing to locate a focal spot. The actual motion control is quite simple. The integration across instrumentation and image processing with the Duet is what I worry about. Am I just buying myself pain and a steep learning curve, or is this a way to make the motion part extremely easy?

I would welcome your thoughts.