Patching Fixtures Using the Binary Switches

[TalJ]

Hi,
I have connected my fixtures using the DMX cables (finaly!).
For a test, I have connected: from the USB to DMX --> Scanner --> Dimmer Pack (which has no output, I guess terminator build in)
Well, the dimmer pack has control of 50 fixtures, so I set the binary switches on the DMX scanner to 51.
However, when I controlled the scanner through freestyler, some of the other fixtures from the dimmer pack were flashing as well.
I have tried setting the scanner to a higher value, and patching it accordingly in freestyler, but still I get the same result. I noticed that when I control fixtures from the dimmer pack, the scanner is unnafected, so I am guessing that the fixtures from the dimmerpack are accepting signals that are sent specifically to the scanner.
Any ideas whats wrong? Just out of curiousity...say the dimmer pack does have an output and I just don't know about it (the dimmer pack is built into our booth's wall and most of the switches in the back can only be exposed by removing the dimmer from the wall...which isn't something I am very happy to do..
So if I don't have a terminator connected...what kind of issues should I expect?
Thanks in advance,
TalJ

[remco_k]

Hi,
Well, the dimmer pack has control of 50 fixtures, so I set the binary switches on the DMX scanner to 51.
TalJ

And what tells you that the dimmer pack has a start address of 1? Is it set that way? Did you check that?

The problems you are describing are typically fixture address overlaps. Like your dimmer starts at (lets say) channel 20 and ends at 69.
While your DMX scanner starts at 51 and ends at 61.
Now, when you control your scanner, then the DMX dimmer will respond on its internal 11 to 21 channels.
Nothing to worry about, just set DMX addresses so that none of the fixtures overlap eachother.

If this is not the case, then you probably misunderstand the way you can adress your scanner or dimmer. Please provide make and model number then, include the way it is configged (if it has dip switches, tell it like 0001011011). Maybe we can work things out together. If possible, make a few pictures.

And last, if you did not misunderstand this, then there is the termination problem. You _have_ to find out if the dimmer terminates the line. If not, make it so.
That is pretty easy: make your own passive Y XLR splitter. Buy 2 XLR Females, 1 Male. Make your own Y splitter. Just solder pin 1 to 1, 2 to 2 and 3 to 3.
Important: Use 2 short DMX cables no longer than 10 cm or so, solder them in the Male XLR and on each end the female XLR.
Use your new passive Y splitter to connect the DMX dimmer only. The other 'output' of the Y splitter is now the DMX output wich you can use to put a terminator in. Don't use the output to connect more DMX cabling or devices as that could give trouble.
Ofcourse you can just solder a 120 Ohm terminator in the last XLR connector that goes in your DMX dimmer as a terminator. Should work okay, either way, you have to be shure that the DMX dimmer itself does not terminate!

In case of someone else reading along this topic thinking that this passive Y splitter can be used to drive 2 seperate DMX cable runs of some length more than a meter or so: it can't and *will* go wrong big time. Use an active DMX splitter for that instead.

[TalJ]

Hi,
Sorry for the delay, the make of the dimmer box is Strand Lighting. I'm trying to digg up the manual from the records in school, and they might have it for me tomorow, so I will know the exact model.
I have connected the scanner to another set of small dimmers that we use in school for small discos (they each have 4 channels), and it works perfectly!
I am not very comfortable with soldering cables together..so I ordered a few terminators. However, with the set up of the small dimmer boxes and the scanner I didn't run into any problems - without using a terminator.
I am very happy with freestyler!
Thanks,
Tal

[remco_k]

not sure if I am on the right track here or not

DMX512 can only control 32 fixtures

Thats not the limit of DMX512, thats a limit people think is a maximum number of fixtures you can connect on a single DMX cable run without causing too much loss of signal because of all the connectors and other losses (e.g. length of cable) and interferences.
Therefore everyone advises that if you need to connect more than 32 fixtures, you use a active DMX splitter that 'copies' the DMX signal from one input to several outputs or you use a second DMX512 universe for the next 32 fixtures. However not all desks and FreeStyler can control more than 1 DMX512 universe.
So, if you want to use more than 32 fixtures you could use an active DMX512 splitter. Then you can connect 32 fixtures on each output. All of the fixtures can have their own address. So in fact DMX512 can control 512 dimmers attached to 1 DMX universe via an active DMX splitter. Controlled by FreeStyler and your favorite DMX interface.
Where the number 32 comes from, how its determined I have no idea. I guess thats a number from practical references.

Remember: I'm not telling that you can't connect more than 32 devices without using an active DMX splitter. It could be working great without it. Its just not what most people do, just like not using a DMX terminator there is a risk to this.
But the DMX512 protocol itself has nothing to do with it, neither is FreeStyler.
Just address all the devices properly, make sure there is no overlap (never!) and you'll be fine.