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    brucek
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CEM+ & CEM3 Back planes and DMX Input question/suggestion

So seeing the Sensor backplanes in the current Backstage made me think:

The DMX Input connector (J10) does not include DMX B on pins 4-5-6 allowing easy Daisy-chaining of DMX A & DMX B from rack to rack to rack using CAT5 because......? Because why?

Is there any reason that DMX B does not also connect to J10 in the back planes?  This would make it much nicer when daisy-chaining both DMX A and DMX B between racks.  Right now, you have to split the DMX to J10 & J11 on one of the racks.  I would love to see DMX A & B landed to J10 & J15. 

Just my thought.... 

 

  • We used USITT standard wiring for DMX input.

  • in reply to dnorth

    Really? Doesn't USITT standards ONLY address DMX on a XLR connector?  As for CAT5, I don't know what actuale USITT standards says, but many manufactures put DMX-B on another pair in the CAT5  (just like ETC does on J15)  I just want a clean way to chain 3 or more racks together using CAT5 cable. 

  • in reply to brucek

    Table 4 - Connection Schedule for DMX512 equipment using IEC 60603-7 8-position modular

    connectors

    Pin (Wire) # Wire Color DMX512 Function

    1 white / orange data 1+

    2 orange data 1-

    3 white / green data 2+ (optional)

    6 green data 2- (optional)

    4 blue Not assigned

    5 white / blue Not assigned

    7 white / brown Data Link Common (Common Reference) for Data 1 (0 v)

    8 brown Data Link Common (Common Reference) for Data 2 (0 v)

    drain

     

    Now, we made this change very many years ago prior to the standard and we have applied it to Paradigm, Sensor+, Sensor3, SmartPack, SmartSwitch, wallplates and more.  Changing this for Sensor would require a change in all places which is not a small task.

    Besides, if three or more racks are being controlled in a system, my recommendation is to move over to ethernet control.

  • in reply to dnorth

    So, I was wrong, we don't follow the recommendations, but it's all coming back to me why.  Like I had said, we did this prior to the standard and we never changed it because of the size of the change.

    DMX is so 1986....let's move on to ENET!

  • in reply to dnorth

    (so 1986?....why not so revised-1990?...or revised-whenever-with-way-too-silly-labeling)

    Well new dimmers with old board or existing dimmers = still-need-DMX.  And CAT5 for DMX = Much less $$$$ then '9729.

    So how big of deal is it when the DMX cable type changes within a cable run.    I have always assumed It was better to use CAT5 to jump racks when CAT5 is run from the house, and use '9729 to jump when '9729 is run from the house.  It would seem to me that changing cable types mid-stream is asking for reflections, etc.  

    What about  landing the second universe's ground when no second universe is used.  Does it really add significant capacitance?   Maybe I need to try this on my bench with a 1000' spool of CAT5 and a scope?

    Anyway, I personally don't see why changing the pin out for J10 (or J11)  would mandate changing the pin out anywhere else.  Hey, it could be out little pin-out secrete

     

     

  • in reply to brucek

    Changing a cable type mid-run is not desired according to the standard and it is suggested a opto or similar device be used at the transition.  I,however, have not seen issues and would not be concerned at all about the cable change.

    Also there should be no issues with landing the second common [I assume you mean common] when the second universe is not used.  There will be no problems.

    So wait, are you trying to save cable or connections?  You can send two universes of DMX down one CAT5, although I wouldn't, and terminate to the two connectors.  You can do what you want to do without problems.

    David

www.etcconnect.com