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Educate Me


Jim Hans

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I, like most of you, have been setting up for weeks. As I have been setting up I have been testing via my computer. I finished setup on Sunday with a total of 8 controllers. Tested via the computer Sunday night and everything works great. HU finds all controllers and sequences run the lights.

Last night I set up the DC MP3 and FM transmitter. I plugged the Cat 5 into the DC MP3... nothing. No lights on it... dead. Plugged the Cat 5 back into the computer; everything is working great. Now panick sets in. How am I going to get a new DC MP3 in time for my pre-lighting party this Saturday. On a hunch I switched out the Cat 5 cable that ran from my computer to the first controller. When I plugged the new Cat 5 into the DC MP3 it worked! So problem solved, everything now works.

But here's where some of you networking experts can help educate me (we all want to keep learning). Why would the Cat 5 cable work when plugged into a computer but not the DC MP3? Obviously the cable is good?? right??? Educate me please.

On a side note, once I got everything running and I was testing the DC MP3 and FM transmitter by walking around with a radio to make sure things were good I looked up and I had 3 cars pulled over watching the show! I had to go apologize to them for turning it off.

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assuming you plugged it into the same rj45 in the dc-mp3, a couple possible reasons (and realize, i've never used a DC-MP3):

1. loose rj45 socket on the dc-mp3...one or more pins not making solid contact inside the socket, second cable, unplugging and plugging back in, fixed it.

2. you have one or more bad conductors in the first cat-5..used by the dc-mp3, but not on the LOR controller side.

can you duplicate the issue consistently with the suspected bad cat-5?

You may find one of these a real help..i just picked one up as i couldn't find my old one. its a little more expensive than the monoprice deal, but i had it in 3 days:

http://www.ebay.com/itm/280737957216

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Are the 2 cat5 cables the same length? Not sure if the DC-MP3 is powered the same was as the mini-director or not, but I know there is a desired maximum distance that the director can be from the controller in order to power it properly (I assume it is a voltage drop issue with the longer cat5 cord).

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I was able to duplicate it several times. I plugged the assumed bad Cat 5 into both DC MP3 Cat 5 jacks with the same result so I know it's not a bad jack. My suspicion, as you indicated, is that one of the wires in the Cat 5 cable is bad or isn't connecting well and it happens to be a wire that the controller doesn't need but the DC MP3 does. Just rying to understand.

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Surfing4Dough wrote:

Are the 2 cat5 cables the same length? Not sure if the DC-MP3 is powered the same was as the mini-director or not, but I know there is a desired maximum distance that the director can be from the controller in order to power it properly (I assume it is a voltage drop issue with the longer cat5 cord).


The one that would not work is a 100' Cat 5 and the one that worked is a 30' Cat 5. BUT..... this same 100' Cat 5 worked last year.
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Jim Hans wrote:

Surfing4Dough wrote:
Are the 2 cat5 cables the same length? Not sure if the DC-MP3 is powered the same was as the mini-director or not, but I know there is a desired maximum distance that the director can be from the controller in order to power it properly (I assume it is a voltage drop issue with the longer cat5 cord).


The one that would not work is a 100' Cat 5 and the one that worked is a 30' Cat 5. BUT..... this same 100' Cat 5 worked last year.

From the manual:

The DC-MP3 is normally powered by the nearest Light O Rama controller or a USB485B PC adapter. Use a 50’ or less CAT5e LAN cable to connect the DC-MP3 to either of these devices. Longer cables may have an unacceptable voltage drop that may cause erratic operation of the DC-MP3. http://www.lightorama.com/PDF/DC-MP3_Man_Web.pdf

Maybe this qualifies as "erratic" operation--works one year and not the next. :P (in all seriousness, not sure what other issues might affect that, meaning for example does how/where the cable was run one year compared to the next affect that erratic behavior).
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Paul Roberson wrote:

Use a power brick to power the DC MP3 and then try the 100' cable. It will probably work fine.

I did buy a power supply from lor for mine.When i try to use it with the power supply hooked up it messes up my fm transmitter.My problem was just one bad cat5 cable that worked when hooked up the the pc,but not with the director.
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Exactly. All good points. Bottom line is that changing Cat 5 cables fixed it. It is just the WHY of it that bugs me... I'm the type of person that just hates not knowing why. Thanks one and all for the responses!

Raining tonight so I want to run the show to see if anything blows in the rain... more questions may follow!

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I've never used the DC-MP3, but CAT5 uses only 1,2,3 and 6
(orange and green pairs) RS-485 usually uses 4 and 5 (blue pairs) and POE apps use 7 and 8 (brown pairs) so if the Orange and green are good, you will have PC-CAT5 comms, but the Brown and blue pairs may have a bad connection or broken wire, preventing other things from working.

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This is just a guess but I think the people here are on the right track.. The DC-MP3 is a passive device. IT gets its power from " the nearest LOR Controller. Just like the old style telephones. A very low voltage is sent down the wire to make your old phones ring.

My guess is that the DC-MP3 uses the pair two on the RJ45 to power the device and Pair one to transmit Data.

On you PC using the RS-485 it is powered from your PC and can transmit a much further distance.

So like others have said.. the voltage drop on a 100 ft cable is to great to run the device.

just my two cents...

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pixeldigger wrote:

I've never used the DC-MP3, but CAT5 uses only 1,2,3 and 6
(orange and green pairs) RS-485 usually uses 4 and 5 (blue pairs) and POE apps use 7 and 8 (brown pairs) so if the Orange and green are good, you will have PC-CAT5 comms, but the Brown and blue pairs may have a bad connection or broken wire, preventing other things from working.

Apologies in advance for nit-picking, but...

CAT5 includes all 4 pairs (pins 1 through 8).

10BaseT and 100BaseT (Ethernet) use pins 1, 2, 3, and 6. (1000BaseT, Gigabit-Ethernet uses all 8 pins.)

PoE uses either pins 1,2,3, and 6, or pins 4,5,7, and 8. (The choice is made by the equipment manufacturer.)

LOR does not use PoE. It uses pin 6 for ground (common) and pin 3 for power (+9-10V).
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