[SML] Servo with RS485- Converting to DMX512?

[Jerry Durand]

While you could make this work, it seems a lot of work for a small benefit.

If I was to do this, I see no reason to replace the potentiometer for
most uses.  It will probably last as long as the bearings, the servo
should be considered a disposable wear item.  In any case, driving one
wouldn't be hard unless you try using an Arduino (not a fan here), that
I wouldn't touch.

Years (decades) ago I upgraded several entertainment devices that used
the model servos under computer control.  I replaced them with stepping
motors since the servos aren't super accurate and wear out fairly
quickly.  The stepping motors lasted for over 10 years of use with no
failures.

Stepping motors are dead simple to operate, I have an old video of
driving a stepper with one of our DC dimmers, no modifications made to
the dimmer.

On 06/10/2016 08:52 AM, Joe D via Stagecraft wrote:
> I came across a system that is used to replace the electronic guts in a radio-control style servo motor.  The potentiometer is replaced with a magnetic encoder, and the servo driver circuit with a new board that has several interface options, which permit you to send digital position commands to the servo. One of the interface options is RS485, which is what really caught my attention, since that is the electrical standard for the DMX512 standard.
>
> RC style servo motors are cheap and convenient packages with motor, gears, and electronics all included. If they were DMX512 capable, I can see many uses in theater.  It might serve to make a projector shutter, a way to remotely trigger a falling prop. If the RC Servo were modified, something can be made to continuously rotate.
>
> In regards to customizing, they have the following in their literature;
>    Programmable: The 01™ Supermodified servo controller utilizes our PicoMCUTM 
>    development board with an ATMEL ATMega328P running at 20MIPS. Our 
>    controllers can be programmed through the UART or RS-485 interface as it 
>    comes pre-programmed with a bootloader. 
>
> Here are some specs for their driver circuitry;
>    The 01™ Supermodified kit utilizes the Freescale MC34931 
>    motor driver IC. With a current capability of 5A (7.8 Amps peak), current 
>    feedback, multiple protection functions and operating on a range of 4.5-24V
> However, I suspect that their tiny board would not handle that much current, without adding a heat-sink.
>
> I investigated what it might take to get over the learning curve to write programs for the ATMega328P. It does not even seem that they release their source code. But,even if they did, I decided it would just be too much to take on. 
>
> I wrote 01Mechanics, to ask them if they would be willing to do the modifications to their code, to work with DMX512, if I provided them with the specs, but they have not responded in over a week.
>
> Perhaps one of our group would like to take on this project.  Here is the link to the source and some of pricing;
>
> Zero One Mechatronics
> www.01mechatronics.com
>
> Hitec HS-311 Standard - Supermodified Servo [Their already modified servo]
>    60 Euro = $68 USD
>
> SuperModified V3.0 for RC-servos [Just the guts to do the mod yourself]
>   55 Euro = $62 USD
>
> Joe Dunfee
>  jdunfee12 at yahoo.com
>
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-- 
Jerry Durand, Durand Interstellar, Inc.  http://interstellar.com
tel: +1 408 356-3886, USA toll free: 1 866 356-3886

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