controller order setup

[Philip]

I was going back over my halloween sequences and noticed something in my setup
the layout of my yard verses the computer location is off

I know that in the hardware configuration the units do not have to be setup sequencially but...
Do the LOR units have to be in order when setting up the hardware or can I branch off from one unit to two others using the two phone line connection points?


maybe the picture will show it better, I'm currently setup to run this as the black lines show, is this ok, or do I need to run the cords as the blue lines show?

Attached files

[Steven]

The black line configuration will probably work, but it's not the way an RS485 network is designed. It's kind of analogous to connecting 20 amps of lights to a 20-amp circuit - It will probably work, but you're pushing the limit.

The reason is that the RS485 signal travels through the network until it reaches the ends. In an industrial RS485 network, like DMX, there are terminators (resistors) on each end of the network to prevent the signal from bouncing back and causing problems. When you connect the network in a "Y", as in your black configuration, it adds another point where the signal may be reflected.

I say it will probably work because you're using phone lines, which cause a fairly high signal loss. This helps to attenuate the reflections.

A better configuration is this one, with the red lines. There are no "Y"s in this network.


Attached files

[rwertz]

In the topic below Dan states “If it works it works”:
http://lightorama.mywowbb.com/view_topic.php?id=15604

I’ve had issues “branching out” on older (parallel) communication busses at work. The problems it created were intermittent and very difficult to troubleshoot. So, my practice will always be to use a daisy chain connection.

[-klb-]

rwertz wrote:

In the topic below Dan states “If it works it works”:
http://lightorama.mywowbb.com/view_topic.php?id=15604

I’ve had issues “branching out” on older (parallel) communication busses at work. The problems it created were intermittent and very difficult to troubleshoot. So, my practice will always be to use a daisy chain connection.

I'll second the comment that it is one of those things that if it works, it works. If it doesn't, or it isn't reliable, there aren't any good recommendations on how to make it work in that topology.

Because any variance from the daisy chain is not part of the RS-485 standard, I personally wouldn't expect any technical support in any configuration other than daisy chained. So, if you do hook things up with a Y, and you have any issues between the control PC and the controllers, the first step will be to switch over to the blue line layout to see if the issue goes away..

- Kevin

[Philip]

it may just be easiest to follow the blue path and stick with CAT5, plus it only requires a slightly longer initial cable from the pc to unit 2

[michael.farney]

Steven wrote:

[snip]
I say it will probably work because you're using phone lines, which cause a fairly high signal loss. This helps to attenuate the reflections.

A better configuration is this one, with the red lines. There are no "Y"s in this network.

I ran 3 Y's in 2007 using the 3rd data port on the LOR cards. It did work flawlessly, and I used mostly phone cord. I had NO CAT5 after any splits. Also, all my phone cables were either 25 feet or 50 feet, even when connecting controllers 2 feet apart. The fact that every controller had a minimum of 25 ft cabling between every run probably killed any reflection. It does work, but your milage may vary.