[SML] DMX/Programmable Winches/Hoists

[Jerry Durand]

On 06/29/2016 06:49 PM, Bruce Cooper via Stagecraft wrote:
> DMX is a one-way system, where the console fires off DMX values and 
> just expects that the system will end up in the right state.  With 
> lights, this poses no life-safety hazard.  With winches, even a 10 
> pound weight moving into head/meatspace at even reasonable speeds [< 
> 2ft/sec] can do some serious damage.
>
> IF there is any life safety risk at all, I personally wouldn't ever 
> use DMX controlled winches, no matter how light the load on the end.  
> Getting caught in moving winch line shouldn't be forgotten as a 
> possibility.
>

I designed/built a custom winch control for an SML member (hope it's 
still working!).  That uses DMX cable but that's as far as it goes.  The 
remote sends constant keep-alive data with checksums to the main relay 
box.  If that doesn't like what it hears it will rapidly stop all 
movement.  If the processor in the relay box crashes, all movement is 
also stopped.

On top of that there's the big red E-STOP button on the front of the 
relay box where someone could be stationed, that kills power to the 
relays.  It also needs a key to remove the E-STOP so hopefully the area 
has been checked for safety before that is done.

-- 
Jerry Durand, Durand Interstellar, Inc.  www.interstellar.com
tel: +1 408 356-3886, USA toll free: 1 866 356-3886
Skype:  jerrydurand