Timeline for How to test a DMX splitter
Current License: CC BY-SA 4.0
18 events
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| Sep 15, 2018 at 11:37 | comment | added | Michel Keijzers | Now I understand what you mean. I don't think we ever need that order (controller->led->splitter->led->terminator). Probably when we would have a very complicated light setup, but we only use the splitter not to have too many cables. Besides, my enclosure is already very full :-) ... but good to know that possibility exists too (maybe if later I need to build another one). | |
| Sep 15, 2018 at 4:18 | comment | added | Maple | You posted photo of DMX splitter 4MKIII earlier. Look at the schematics on top of it. Two inputs on the left directly wired to two "thru" outputs. They also fan out to 4 other outputs via square boxes representing isolation (6N137 in your device) | |
| Sep 14, 2018 at 18:38 | comment | added | Maple | What I described is not a "booster", because "thru" jack is wired directly to input jack, no boost here. It is a simple wiring option that makes physical placement of the splitter more flexible. For example this could be a single RS485 chain: Controller -> LED -> splitter -> LED -> Terminator. Then other 4 chains can be attached to the splitter in the middle. RS485 supports more than 30 nodes on the line. By connecting controller directly to splitter you achieve better isolation (i.e. controller protection), but you are under-utilizing the driving capacity of controller output. | |
| Sep 14, 2018 at 11:11 | comment | added | Michel Keijzers | Thanks Maple for again good explanations, and yes, as you say it's indeed a short circuit for pin 1. I guess for the manner you describe it's like a 'booster', but for our purposes it's just a splitter, so I put at the input and all outputs a 120 ohm 0.5W resistor. And have to make some more termination plugs for the end of the daisy chained DMX devices. | |
| Sep 14, 2018 at 10:07 | comment | added | Maple | And yes, thanks to isolation you pretty much have 5 separate RS485 networks. One begins with controller and ends with splitter. Four begin at splitter and end somewhere (potentially via many daisy-chained modules) with termination plug. BTW, if you remove input resistor and add "thru" jack to the splitter, you'd be able to place it anywhere in the controller's chain. Of course then you'd need a termination plug on "thru" output if splitter is the last device on that network. | |
| Sep 14, 2018 at 9:55 | comment | added | Maple | You can put 1 to output if the output is 1 itself. It's when output is at 0 (i.e. close to 0V) that bad things happen. Or the opposite - output at 1 (i.e. close to 5V) and you connect it to ground. This is a simple short circuit, no magic here. You don't connect hot and ground wires together after all. | |
| Sep 14, 2018 at 8:30 | comment | added | Michel Keijzers | Thanks for the explanation, I should see the circuit (and connected DMX devices) as five different chains (one input, 4 output). I was not aware of frying a chip if you put 1 to an output (never tried, so thanks for the warning). | |
| Sep 14, 2018 at 5:39 | comment | added | Maple | 5) Once again, pin 1 is an output connected to Vcc. If it tries to output 0 this will instantly fry the chip. There is no reason whatsoever to connect it to anything. 6) Normally, RS485 must be terminated at both ends. Terminator takes care of one end of a chain. But splitter sits at the other end. Yours is a special case. Sometimes resistor can be omitted on the transmitter side IF transmitter is at the beginning of a chain AND transmission is always in one direction. So, it is your choice. But it is not "instead". You need either both, or one at the end. | |
| Sep 13, 2018 at 13:11 | vote | accept | Michel Keijzers | ||
| Sep 13, 2018 at 13:10 | comment | added | Michel Keijzers | Thanks for the comments, About 4: indeed, need to add it (in model). About 5: Is that a problem? It's an unused pin anyway (thought it would be easy for soldering. I will check the datasheet if it is used. About 6: I did not add them in the circuit neither, the end of each chain has a DMX terminator/120 ohm resistor. Isn't that a better solution instead of putting 120 ohm resistors in this circuit? I will use for the tests DMX cables, not XLR cables. | |
| Sep 13, 2018 at 0:34 | history | edited | Maple | CC BY-SA 4.0 |
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| Sep 13, 2018 at 0:28 | comment | added | Maple | Added 4), 5), 6) | |
| Sep 13, 2018 at 0:28 | history | edited | Maple | CC BY-SA 4.0 |
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| Sep 13, 2018 at 0:09 | history | edited | Maple | CC BY-SA 4.0 |
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| Sep 13, 2018 at 0:04 | history | edited | Maple | CC BY-SA 4.0 |
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| Sep 12, 2018 at 10:31 | history | edited | Maple | CC BY-SA 4.0 |
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| Sep 12, 2018 at 10:24 | history | edited | Maple | CC BY-SA 4.0 |
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| Sep 12, 2018 at 10:18 | history | answered | Maple | CC BY-SA 4.0 |