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CAT5 wiring question


TheJackal
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You can do either way although I've read about people reporting problems with splitters when using outside due to the weather. The controllers are set up with the RJ45/CAT5 connectors to easily daisy-chain but with RS485 communications, it doesn't make too much difference. Example is, I use the ELL's which have two connectors going out. I run two directions from it and daisy chain from each.

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I think you both should google RS-485 White papers. Sorry gents this is not your home Eithernet, but RS-485 protocol. LOR just uses Cat 5 cables (notice I did not call them Ethernet cables). To make easier for the people who do not own the tools or skill set to make their own. It also a fast and quick way to plug in the cables verses having to remember a color code and install each wire under a screw (fool proof for the most part).

 

Just a brief bit of info. RS-485 should be wired daisy chained. Aka top diagram above.

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I wasn't calling them TCPIP or ethernet either, rather I did refer to them as RS485 just using Cat5 wire and RJ45 connections. My daisy chains always end at a controller, hoping LOR took termination into account in their design.

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LOR tested typical configurations with and without termination, and found that at 56k, with the chips they are using, most of the time termination made no difference, but incorrectly applied termination hurt performance. Occasionally adding termination helps, but usually people looking to try it actually have a bad cable, or bad jack actually causing their problem.

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Thanks for the info dgrant.

 

Max - I didn't call them Ethernet cables either ;) I could probably make my own. But, I'll just go PC > 2 of the controllers and then use ELL's to get to the other 3.

 

Why are you using ELLs for?  Your place isn't that big.  Seems to me one expense you don't need.

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Why are you using ELLs for?  Your place isn't that big.  Seems to me one expense you don't need.

Simple actually, the show computer is inside and no direct path to run the Cat5 cable from this particular room to where the controllers are, without going all the way up a wall, through the second floor, into the attic, across and back down out in the garage, then outside from there. ELL was the easy way to accomplish it without wires. Works well too. Although, now I'm going to get into RGB so that creates the same issue but ELL's aren't going to help me.

 

Oops, answered the wrong person's question to someone else..please pardon me.

Edited by dgrant
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Why are you using ELLs for?  Your place isn't that big.  Seems to me one expense you don't need.

Looking at my house (since you remember it) There will be 2 controllers on the left (garage side) and the other 3 on the right. I need to come across the driveway. I guess I COULD run a CAT cable through one of the expansion joints or get a 100 footer and run back to the garage. I'm glad I have options.

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Well, see the reason I mentioned Ethernet is cause of the topology that the second diagram represents is a star topology. A no-no with RS-485. Also a splitter might be one of those new fangled words that so many around here toss about. Might be another word for a switch as that which is common in an Ethernet network. As a person trying to help. Ya just never know the technical background of the person at the other end of this forum. So, forgive me if you already knew not to get caught up in the Ethernet stuff. But yet the op did not know that with RS-485 a daisy chain topology is the proper topology. And nor did you dgrant. Doing anything other than a daisy chain is asking for problems. As you sort of noted, yet you suggested that he could, just some had problems.

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Well, see the reason I mentioned Ethernet is cause of the topology that the second diagram represents is a star topology.

Understood.

 

Here's a picture of the front of my house in Visualizer. There is more room to the left (we're the last house on a cul-de-sac) and about 6-8 ft more on the right. I'm not going THAT wide though. So there will be 2 controllers on the left and 3 to the right. The house (measured the eaves) is 50 ft wide. The Director will be inside the garage (left or right, I'm not sure). If I could split the CAT at the garage (1 into 2...not 3 like in the picture), it would make things easier. If not, it would be a pretty long run from left to right (but, it can be done) OR use an ELL.

post-12100-0-72407100-1390186855_thumb.j

 

P.S. My wife has made it VERY clear......the tree is staying.

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I happen to know a lot about RS485...you might be surprised. Where I worked, it was only used on a couple of very greatly older systems. All the newer, faster systems were TCPIP via laser viber which makes RS485 as old as the stone age. Got a lot of knowledge in GPIB/HPIB as well. My assumptions are that LOR takes into account the proper or needed terminations or lack thereof, that works best for their design. I may not know what you do which is fine. I'm always willing to learn new things. If I'm wrong on anything, I want to know so that I can learn what's correct.

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I may not know what you do which is fine. I'm always willing to learn new things. If I'm wrong on anything, I want to know so that I can learn what's correct.

I don't have any kind of technical training. Everything I know about electrical, plumbing, etc etc, I learned by reading,watching others and, in some cases, trial and error. I wasn't sure if I could split the cable 1 into 3, so I asked.....and I'm glad I did.

Edited by TheJackal
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Interesting thread, I being new here was not sure why the Cat5, Rj45 set up was used here. I thought that it may become necessary in a future release or something. In most of my application  most of the controllers will be mounted in my basement the thus the topology requirements are easy to meet, but as I expand I will be mounting controllers remotely and it sounds like I will need to pull 2 cat5 cables for all locations out side the basement. This may be a dumb question but is there latency issues caused by longer cable runs? The longest I should have is 120 to 150' one way so to achieve the "daisy chain" between to elements that are each 120' away I would have 240' there and back to the first element and then another 120' to get to the second element,

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Well, see the reason I mentioned Ethernet is cause of the topology that the second diagram represents is a star topology. A no-no with RS-485. Also a splitter might be one of those new fangled words that so many around here toss about. Might be another word for a switch as that which is common in an Ethernet network. As a person trying to help. Ya just never know the technical background of the person at the other end of this forum. So, forgive me if you already knew not to get caught up in the Ethernet stuff. But yet the op did not know that with RS-485 a daisy chain topology is the proper topology. And nor did you dgrant. Doing anything other than a daisy chain is asking for problems. As you sort of noted, yet you suggested that he could, just some had problems.

 

LOR offers a Network Repeater  that "Has one RJ45 jack on the front and two RJ45 jacks on the back to allow the network to ‘Y’ "

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Great thread guys, nice job!   This helps to answer a few questions I had but haven't asked yet.

 

This last season, I tried two experiments.  The first was to create a homebuilt passive "Y" cable for use on our LOR network made by simply taking two factory CAT-5 cables, cutting them in the middle and soldering the wires of three of them together - matching the wire's color codes.  This gave me a simple One-in-Two-Out  Y cable that helped me out of a jam.  It was dark with visitors out front and the output daisy chain port of one of my controllers suddenly decided to not work.   The cable worked perfectly until I could get a repair done to the controller.   

 

The second experiment was to add a simple 5 port NetGear HUB (NOT a managed switch) to our RGB (E1.31) network which allowed me to run one trunk line to feed 3 SansDevices controllers on the other end.  This worked perfectly too. 

 

I wasn't sure if we were just lucky or whether this was a viable configuration option.  It sure appears that those with significant experience sure caution strongly against it.   My oscilloscope is broken so I couldn't analyze the signal, and I don't have access to the LOR drawings.      For curiosity sake, I'd be interested in hearing a little more in-depth technical answer as to why these options are a bad idea.

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Nam_1956,   Thank you for your service sir. 

 

Have you considered just sending one data cable out of your basement to your first outside controller, then daisy to your second and other future controllers from there?   It would be simpler and more inexpensive.   It is also consistent with the daisy chain implementation if you started from your last basement controller output data port.

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E1.31 usually (nearly always for our purposes) runs on Ethernet, so Ethernet switches are appropriate and correct.

LOR signaling is RS 485, which optimally runs on more expensive cable with no defined connector or pin out, except that the two data pins shall be on a twisted pair if available. But 100 ohm twisted pair is a decent approximation of the ideal cable for rs485. Cat5 cables are 100 ohm twisted pair, and are readily available, and reasonably cheap.

The standard does allow for short stubs off the daisy chain. For example, many devices have the in and out directly connected, and a few inches of wire running to the electronics. Even LOR has the two jacks directly connected, and about a 1 inch of circuit trace to get to the chip.

But, imagine that the daisy chain is a long piece of 2 inch pipe. You can talk in one end and easily be heard at the other. You can add a few short stubs to the side, and still be ok. But as those stubs get longer, you start to loose ability to understand at the far end. Each stub now has it's own resonance, and is adding both a reflection and a resonance back into the main pipe, and the side stubs get longer, the delays in the reflections get longer, and more out of phase, making the real signal in the pipe more unintelligible.

The electrical signal acts much like the speaking pipe example. Sometimes it can work, but as the branches get longer, the odds go against it. And LOR is fully within their rights to not provide any assistance troubleshooting if a branched network stops working mid season.

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LOR offers a Network Repeater  that "Has one RJ45 jack on the front and two RJ45 jacks on the back to allow the network to ‘Y’ "

Thanks Ken, as I started to read from the last post I read yesterday I came to the same thought. If only need to split to two cables. Gents Ken beat me to it and I agree with Ken. Best way to split is to use the repeater.

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Thanks klb you explained good reasons to stay away from stubs. I will also point out that LOR are now releasing devices that can run at 115Kbs I think it is. Verses the current 9.6Kbs. Quite a jump in speed. And with this there is no free lunch. There is a trade off. This trade off is that the signal is more sensitive to stray noise and the actual wiring of the network. I am sure many of you know that Cat5 had a 300Mhz limit and Cat5e had I think 500 Mhz limit. Then along came Cat 6 with 1Ghz limit I think it is. The Mhz translate into Mbs. As the frequency went up the quality of the cable has to go up. So, even though the frequency compatiblity of Cat5 is still many times greater than 115Kbs. The connections, location of the wire in relationship to noise producing items, and kinks in the cable can kill the signal.

 

Now I am going to step out from klb's thinking and say that if you are having major problems with lights blinking when they should not or coming on and stay on till the end of that song. Then a termination resistor might be needed in the last controller. I will concede that you need to really check each of your cat5 cables and the sockets on each board. We have loose sockets with back solder joints on the back of the board. WE have the little wire contacts in the sockets that get smashed down and need to be lifted carefully. Then there are the bad terminations in the plugs or the broken wires in the cable (solid wire only will flex so many times before it breaks).

 

Ok, sorry got a little carried away.

Edited by Max-Paul
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The sound pipe example does continue to work. An open pipe end does reflect air waves, or else a flute would not play a note. If you put a suitable muffler on the end of a flute, or our sound pipe, you would no longer get the reflection off the end. The flute would not play, and someone listening just before the end of the pipe would hear a cleaner signal.

It certainly can't hurt to try a terminator if you are having lost command issues. We have a couple of experienced users who have cleared up their issues. But we have also had several who reported only partial improvement with a terminator, and tracking down a connection fault actually fixed it. And quite a number who have found bad jacks, or bad from the factory cables.

Also, default LOR is 56Kbps, super speed is 500kbps. So quite a difference, but still roughly three orders of magnitude slower than the 350mhz that most cat 5 and higher cable is actually tested to. Gigabit copper actually only runs 250Mbps per pair, and uses all 4 pairs. It allows for both ends to talk on all pairs at the same time, and still sort out what the far end is saying, opposed to what is cable reflections of itself talking.

But yes, the 10 fold increase does make all reflections, even from just the connectors that much more significant.

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You're talking about the harmonic response of a circuit.  That clears it up for me guys.  Thank-you all. 

 

We'ill keep to the preferred typology in our design, but will also keep my handy dandy Y cable available for emergency operation.    You're exactly right, I used it to feed only one LOR controller off the main line of the higher speed LOR Network (USB-RS485-HS) after I had the output data port on one controller fail.  The two controllers were mounted side by side and the stub was less than 24".   

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It is not simply a copper splitter, it has active electronics to duplicate the signal to a new separate network.

This I understand. Much of what was said above went over my head. But, that's ok.

 

Using long cable to run from one side to the other is cheaper. But, I'm keeping my options open.

Edited by TheJackal
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