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Topic: Controll Nema 17 with DMX (Read 352 times) previous topic - next topic

mateoman

Hi guys,
I try to somehow get my DMX values to controll NEMA 17 Motors. For the most things i know what i have to do. My problems start when i look for a motor driver/motor controller solution. As far as i read i cant convert the DMX values to a GRBL CNC Shield (or at least i dont know how and didnt found any information). The next step was to try L298N Controller which seemed not suitable at all as the heatsink did get hot af in just seconds. As i read a common problem as they transfer too much energy into heat. Now i dont know how to get on as the most shields are too expensive for what i wanna do. Most shields other shields just controll single motors and cost about 20 $. I wanna controll 15 Motors. Any suggestion to relative cheap solutions would help me a lot.

Here are specifications of the motors:

Isolationswiderstand: 100MΩmin.(500V DC)
Wirderstand pro phase: 1.7Ω±10%
Induktivität: 3.7mH±20%
Haltemoment: 420mN.m
Rastmoment: 18mN.m
Schrittwinkel: 1.8°± 5%
Isolationsklasse: Class B
Rotorträgheit: 57g.cm²
Nennspannung: 2.55V
Anzahl der Phase: 2
Nennstrom: 1.5A
Mass: 0.28kg

Thanks for any advices in advance :) Greetings

Robin2

You don't need to use GRBL with a CNC shield. It is just a piece of hardware that holds a few A4988 stepper motor drivers.

If you identify the pins for step and direction for a particular motor then you can write a simple Arduino program to send a step signal at appropriate intervals. The examples in this Simple Stepper Code should work fine for testing - provided you use the appropriate pin numbers.

You may also need to activate the Enable pin for a driver.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

ballscrewbob

Avoid the L298 as it does not really have the current capacity for NEMA 17 except in light use cases.

There are much better drivers available.

Bob.

It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.

mateoman

Thanks a lot i didnt knew that. I only worked with the shield with GRBL for my CNC machine and everywhere where you can buy those its called GRBL shield right in the name :) Have a nice winter holidays! Mateo

MarkT

#4
Dec 05, 2019, 12:50 am Last Edit: Dec 05, 2019, 12:52 am by MarkT
I wanna controll 15 Motors. Any suggestion to relative cheap solutions would help me a lot.

Here are specifications of the motors:

Wirderstand pro phase: 1.7Ω±10%
Induktivität: 3.7mH±20%
Haltemoment: 420mN.m
Rastmoment: 18mN.m
Schrittwinkel: 1.8°± 5%
Nennstrom: 1.5A

Thanks for any advices in advance :) Greetings
Hi, yes 15 motors is a lot - that motor needs at least a DRV8825 module (one per motor), as 1.5A is fairly high.  The L298 cannot drive such a low impedance motor at all, nor would you want to as it takes 4 pins per motor, not 2 with the DRV8825.

The problem you may have is driving step signals fast enough for 15 motors if they need to move simultaneously.  For instance the AccelStepper library can do about 8000 steps/second with one motor on an Uno.

You'll likely need more pins than an Uno, so a Mega or preferrably something faster that supports a step+direction stepper library such as AccelStepper.

Or maybe a few Arduino ProMini's as slaves to just control some motors under direction of a master microcontroller.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

mateoman

I now did bought 2 two Megas as and 2 CNC Shields for them and reduced the number of Motors needed to 10. As the Shield is made for 5 i concluded that work work just fine. Its not so much of a problem to get them all timed right. So lets see how it works. Now i just need to program and try and error everything. Thanks for all quick ansers. Greetings

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