DMX Scroller Problems

[soundtch]

I am working on a four display show where we are using four Wybron ForeRunner scrollers with neutral density scrolls to fade the projectors in and out. We are trying to use an ENTTEC Ode DMX node to control the scrollers through Watchout. The four scrollers are daisy chained together. The first three are working without a problem.

 

The one on the end of the chain is the problem. In several of the cues, it will sometimes open a second or more late, stutter as it's opening, open just to close again a second later, or not open at all. It will only do this when one of the other scrollers has a slow fade at the same time (usually the first scroller). Once the other scrollers have stopped moving, it will not move. If I try to move it on it's own or in time with the other scrollers, it behaves normally.

 

I have one aux timeline for each video cue. Initially, I had scroller cues within each cue's timeline. In troubleshooting, I moved them all to one aux timeline that is the duration of the show with all of the scroller cues. This did  not seem to make any difference. Our electrics department has also swapped out the scroller, retentioned the scroller, and moved the scroller power supply to minimize cable length. None of this made any difference.

 

Does anyone have any idea what I can do to fix this?

 

Thank You!!!

[jfk]

I am working on a four display show where we are using four Wybron ForeRunner scrollers with neutral density scrolls to fade the projectors in and out. We are trying to use an ENTTEC Ode DMX node to control the scrollers through Watchout. The four scrollers are daisy chained together. The first three are working without a problem.

 

The one on the end of the chain is the problem. In several of the cues, it will sometimes open a second or more late, stutter as it's opening, open just to close again a second later, or not open at all. It will only do this when one of the other scrollers has a slow fade at the same time (usually the first scroller). Once the other scrollers have stopped moving, it will not move. If I try to move it on it's own or in time with the other scrollers, it behaves normally.

 

I have one aux timeline for each video cue. Initially, I had scroller cues within each cue's timeline. In troubleshooting, I moved them all to one aux timeline that is the duration of the show with all of the scroller cues. This did  not seem to make any difference. Our electrics department has also swapped out the scroller, retentioned the scroller, and moved the scroller power supply to minimize cable length. None of this made any difference.

 

Does anyone have any idea what I can do to fix this?

 

Thank You!!!

 

You may wish to consult with a DMX expert, may be a DMX wiring issue.

At least he can monitor the line to see what is there,

both on the ArtNet (ethernet) side and the DMX side of your ENTTEC Ode DMX node / adaptor.

 

What you describe sounds a bit like improper termination of the DMX bus.

The signal bounces back down the line with a slight delay,

resulting in both constructive and destructive interference.

Seen long threads on theater and show control forums on how that is addressed.

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from:  Integrated Controls Inc - DMX512 Protocol Standard

... The DMX512 data signal requires termination at the final connection in the DMX control signal loop. Improper termination is the most frequent cause of DMX problems. A terminator is a resistance at the end of the DMX line. This resistance prevents the DMX data signal from reflecting back down the line and causing data errors and other problems.  DMX receiving equipment should have a "termination" switch or termination option for end of line in the setup. The data signal should only have one termination at the end of the loop, multiple terminations will load down the data signal. If the receiving equipment does not have a built in terminator, then an XLR terminator accessory should be used at the last female XLR "DMX out or loop" connector in the data line connections. ...