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Link 2 DCX's

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jwdrain View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jwdrain Quote  Post ReplyReply Direct Link To This Post Topic: Link 2 DCX's
    Posted: 11 October 2013 at 3:14am
After reading the manual it sounds like you have to link one DCX to your computer with an RS485 cable, then you have to run another RS485 from that DCX's Link B to the other DCX's link A...only the link inputs and outputs on the DCX's look like they're for Ethernet cables?

Also the laptop I was planning on using is a mac - they have no DS485 connection on them. Can you get round that by using a USB - RS485 cable?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote THECANDLEMAN Quote  Post ReplyReply Direct Link To This Post Posted: 11 October 2013 at 9:10am
whats your hoped set up ??
 
5 or 6 way stereo ?? or just need more than 6 outputs ?
 
someone on here will know how to do it another way if its pos ?!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 11 October 2013 at 9:34am
RS485 is just an electronic specification - a protocol. You can transmit it using any suitable cable which can take the 4 signals necessary (if you want full duplex). RS485 is a bit similar to RS232 (which is your standard serial cable) except it has 2 pairs of inverted signals for noise rejection and proper routing (not just a one to one link).

To get them all talking you need to connect the two together with a normal ethernet cable (I assume patch not crossover). Then you need to get the first one in the chain talking to the PC via a serial cable. These two connections should be able to be tested independently of each other.

If you have a PC/laptop with a proper com port in hardware this will help. USB-serial is a possibility but people say that in order to get proper comms with more than one unit you need a proper 5 wire RS232 implementation with handshaking, not the basic 3 wire ground/Tx/Rx.

Apart from that make sure both units have the same firmware, that can't hurt.

Here's another fun one for you, DMX512 is also RS485! But carried down an XLR based cable with 120 Ohm impedance (ideally) and a termination resistor. They often have only 3 wires because communication is one way in that case - the controller tells fixtures what to do, it does not receive status messages back from the lights. Probably some high end DMX gear does implement 5 wire full duplex features. There is also a spec for implementing 5 wire DMX over RJ45 (ethernet) cables too.


Edited by odc04r - 11 October 2013 at 9:41am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote oldskool Quote  Post ReplyReply Direct Link To This Post Posted: 11 October 2013 at 11:25am
So DMX is just RS485? I never knew, thanks for that.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jwdrain Quote  Post ReplyReply Direct Link To This Post Posted: 11 October 2013 at 12:04pm
Cheers for the detailed info Odc!! This is actually still your old crossover in question! She's still going strong :P

I've got an old windows laptop that I suppose I could use, only when its disconnected from its charger for more than about 90 seconds it dies :S

Candleman, my set up is 4 way so on my crossover its split into 6 channels - 1 channel is Y split and on sub, another is Y split and on kick, then there are 2 channels for mid and 2 channels for Highs. My friends running his in exactly the same way but we're linking up next weekend and were thinking of going about linking up the DCX's for it.

Is it possible to just run out of the mixer Master right to one DCX, then master left to the other one?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote THECANDLEMAN Quote  Post ReplyReply Direct Link To This Post Posted: 11 October 2013 at 12:12pm
yeah, then you either need to Y split it so the dcx can have 2 input feeds, to put into input A+B
or you need to change all the inputs to get source from source channel A as in most setting (LMH LMH or MONO) itll look for source A for one side and source B for the other unless you change them all to A
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 4D Quote  Post ReplyReply Direct Link To This Post Posted: 11 October 2013 at 12:13pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jwdrain Quote  Post ReplyReply Direct Link To This Post Posted: 11 October 2013 at 9:57pm
If the outputs on the DCX are summed will they work with just a signal running to Channel A of each DCX? If not I'll just get Y Splits.

I'll read more into linking them via computer, but its next week that this link ups happening so just wanted to know there was another alternative if something went wrong!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 11 October 2013 at 11:23pm
If you want to run two stacks each playing a mono sum of the music, you will need y-splits. If you want to do stereo, you don't need y-splits, just send each stack one channel on input A. No audio passes along the control link so don't get confused about that. 
Stereo is better, do stereo Wink At least for the mid tops, if you sum the subs to mono even with 2 separate stacks, that would possibly give you a bit more beef in the bottom end.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jbinks-v2 Quote  Post ReplyReply Direct Link To This Post Posted: 13 October 2013 at 1:55pm
I think there's a bit of confusion here.

Let's separate the two completely different subjects that are currently being discussed:

1. Linking the DCX units digitally (meaning using the RS485 protocol).
This ONLY allows you to control the units from a PC. It doesn't grant the PC or either of the DCX's access to the other DCX's audio signal.
Generally, there's not much point in doing this. It's so easy to configure the DCX using the front panel and I would assume that your racks will be close to each other anyway (as that's where the power supply will be!) so it's easy to apply the same settings to both units manually.
Alternatively, use a PC Card to save the settings onto and then load into the other unit.

2. Using two DCX's with the same source signal.
If you are doing a "left and right" split, then this is easy! Just feed the "A" input with either left or right from the mixer. Then set the input channel for all the outputs to A. Done. The only thing you might need to bear in mind is if you previously used stereo inputs, and you have any outputs configured to use the SUM, then you will need to increase the output gain by 3dB as you no longer get the "boost" from summing the two input signals.

Hope this helps!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 4D Quote  Post ReplyReply Direct Link To This Post Posted: 13 October 2013 at 2:15pm
Originally posted by jbinks-v2 jbinks-v2 wrote:

2. Using two DCX's with the same source signal.


Using two DCX summing the LF to mono presents a slightly more complex problem

Y split on one input channel or both depending on how many bands are required ho.. or link an output to an input & double the dac process 


    
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jbinks-v2 Quote  Post ReplyReply Direct Link To This Post Posted: 13 October 2013 at 2:19pm
Originally posted by 4D 4D wrote:

Originally posted by jbinks-v2 jbinks-v2 wrote:

2. Using two DCX's with the same source signal.


Using two DCX summing the LF to mono presents a slightly more complex problem

Y split on one input channel or both depending on how many bands are required ho.. or link an output to an input & double the dac process 


    

Yep, I always split the stereo source and send it to BOTH units.

Then simply configure the non-summed outputs to use the relevant input (generally, this means that the left stack will use A and the right stack will use B).
The SUM outputs will have access to both input channels, so no need to make any changes.

I don't like using an output channel as an input for another unit...


Edited by jbinks-v2 - 13 October 2013 at 2:20pm
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