@phaedrux said in Advice for art installation:

Are all 15 steppers for a single installation or for the 3 of them? IT may not be possible to control all 3 installations from a single board. That would be like controlling 3 cartesian printers from a single board.

What does your processed gcode look like? Have you generated something to control 15 motors?

Exactly this is my plan. 3 cartesian printers with 2 extruders each controlled by one MB6HC and three EB6HC. All connected through CAN-FD.
So the GCode would contain many lines similar to this:

G1 F159 X3 Y3 Z4 U3 V3 W4 A3 B3 C4 E3:4:5:6:7:8

Is it possible to store the status of an endstop in a variable?

My goal is to write something like this:

var endstop_status = M119 X
if endstop_status = TRIGGERED
    G1 .....
else
    G1 .....

Is it possible to base a condition on the status of an endstop?

@dc42 Almost perfect. In Gcodes.cpp the code has to be moved from HandleMcode to HandleGcode

@dc42 I checked out the RRF 3.5-dev branch and was able to compile and upload it to my MB6HC. It works! Thanks!

Some comments:
On https://www.reprap.org/wiki/G-code it is specified that after a G93 a G1 F{f} is interpreted as a movement that finished in 1/f minutes. This behavior is disabled by a G94.
E. g. G93 G1 X100 F2 takes half a minute, that results in a classical feedrate of 200mm/min.

Your implementation is slightly different. After a M93 a G1 F{f} is interpreted as a movement that finished in f minutes. It is disabled by a M94.
E.g. M93 G1 X100 F2 takes two minutes, that results in a classical feedrate of 50mm/min.

The code itself works like a charm. I think that your interpretation is even easier to understand. Now I can program my robot to do complex things with a specified timing in minutes without calculating a feedrate. Thank you for your amazing work!

@dc42 The Inverse Time Mode would help me enormously in my current project. I am trying to implement it myself. But I am a bit overwhelmed by the complexity of the code.
Do you already have an idea where the handling could be made in an elegant way?

@phaedrux said in Advice for art installation:

Are all 15 steppers for a single installation or for the 3 of them? IT may not be possible to control all 3 installations from a single board. That would be like controlling 3 cartesian printers from a single board.

What does your processed gcode look like? Have you generated something to control 15 motors?

Exactly this is my plan. 3 cartesian printers with 2 extruders each controlled by one MB6HC and three EB6HC. All connected through CAN-FD.
So the GCode would contain many lines similar to this:

G1 F159 X3 Y3 Z4 U3 V3 W4 A3 B3 C4 E3:4:5:6:7:8

@mrehorstdmd Wow! Your table with a speed of 2,000mm/s is insane!

I do not need that much acceleration. My acceleration will be more in the realm of 250mm/s^2. Top speed should be high, but it can take time go get there. Still your advise on the needed power of the steppers is valuable. Thanks.

Apart from that. Does the plan to coordinate 15 steppers using multiple extension boards sound doable?
Would feeding G1 commands live into the system via the socket on a Raspberry Pi work?

@alankilian Thanks for your hint about GCode macros! If I understand you correctly you are suggesting that I write my own version of G1 that works in inverse time mode. e.g. G93_1

A simplified and untested version:

;g93_1.g
;param.F contains the inverse time (1/s)

var distance = sqrt(param.X*param.X + param.Y*param.Y + param.Z*param.Z + param.E*param.E)

if distance == 0
   G4 S{1/param.F}
else
   var feedrate = distance / param.F * 60
   G1 X{param.X} Y{param.Y}  Z{param.Z} E{param.E} F{var.feedrate}

In an old post it was mentioned that maybe only XYZ are used for the feedrate:
https://forum.duet3d.com/topic/1353/4-axis-machine-feedrate-calculation-and-movement-planning/10?_=1653411553852
They were referring to this:
http://linuxcnc.org/docs/html/gcode/machining-center.html#sub:feed-rate

Is this correct? Are only XYZ used for the distance calculation? Or are all axes and all extruders used for the calculation?

To misuse Duet3d as a generic platform for non cnc applications support for G93 would be great.

"G93 is Inverse Time Mode. In inverse time feed rate mode, an F word means the move should be completed in (one divided by the F number) minutes. For example, F2.0 means the move should be completed in a half a minute. When the inverse time feed rate mode is active, an F word must appear on every line which has a G1, G2, or G3 motion, and an F word on a line that does not have G1, G2, or G3 is ignored. Being in inverse time feed rate mode does not affect G0 (rapid move) motions."

See: https://www.reprap.org/wiki/G-code

Is there any plan on implementing the Inverse Time Mode?

I am planning a huge art installation using multiple steppers. It would be great to get some feedback if this sounds doable using Duet3d.

It basically can be described as three room sized XYZ robots. Each robot has a XY belt driven system mounted from the ceiling that transports a winch. Each winch can lower a steel rope. And on the end of that rope is a sculpture. The idea is that the sculptures perform a prerecorded dance in the space.

Since the setup can be described like an inverted cartesian 3d printer I am planning to use GCode to record the dance. I created an animation in a 3d program and exported that as a list of timed G1 movements. Testing it on my 3d printer worked great. The print head moves exactly as I planned it.
The next step is to do it in large scale. Duet3D seemed like the perfect platform that solves many problems for me. The Duet 3 MB6HC with several Duet 3 EB3HC will have enough flexibility and power to run the up to the 15 steppers that I have planned.

Precision is not important. I am thinking in the scale of cm. The max speed should be about 1m/s. I assume that I need to disable Microstepping.

My plan is that the automation repeats every 30 minutes. To have a smooth movement in curves I am thinking about a resolution of 4 fps (4 GCodes/s). That means that it will be a huge GCode file with 7.200 G1 instructions surrounded by one while statement. If I really build the installation in full size, these G1 statements will have positions for XYZUVWABC axes and 6 extruders in every line.

What do you think about this? Does this sound insane or doable?

I am additionally thinking about making a part interactive using a Raspberry Pi. I am imagining that a program checks inputs, generates the next coordinates and sends G1 commands over the dcs socket. This has to happen multiple times per second.

with open("dcs.socket", "w") as f:
    while True:
         time = time.monotonic()
         input = getInput()
         pos = calculateNextPositions(input)
         federate = (pos – old_pos).length() / (time – old_time) * 60
         f.write(f"G1 X{pos.X} Y{pos.Y} ... F{feedrate} \n")
         old_pos = pos
         old_time = time

Would this work?