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Ready to put up lights but have one question! |
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Pony_God
Senior Member Joined: 01 Sep 2008 Location: Naples, FL Online Status: Offline Posts: 551 |
Quote Reply
Topic: Ready to put up lights but have one question! Posted: 14 Nov 2008 at 8:00am |
I'd be happy to build a little terminator that just plugs in if it fixes a single error, and it it follows the RS485 spec better.
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JonB256
DMX Joined: 19 Dec 2007 Location: Granbury, TX Online Status: Offline Posts: 130 |
Quote Reply Posted: 13 Nov 2008 at 9:38pm |
Looked around and found one source that said the far end should be terminated with a 120 ohm resistor. It also said the total daisy chain could be 1.2kilometers long. I'll ignore both items. |
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JonB - D-Light user
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Pony_God
Senior Member Joined: 01 Sep 2008 Location: Naples, FL Online Status: Offline Posts: 551 |
Quote Reply Posted: 13 Nov 2008 at 11:36am |
Does it really matter how far? What's entailed in termination? resister between wire X and Y?
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LightsOnLogan
Admin Group Joined: 11 Oct 2007 Online Status: Offline Posts: 3187 |
Quote Reply Posted: 13 Nov 2008 at 10:20am |
The delay on the scale of our displays can be measured in nanoseconds (that's 0.000000001 seconds). The COM port speed introduces more delay than the wire ever will, and for most applications even that isn't noticable. There is more delay between the listener's ears and their car speakers than there is in the wire or COM port. Don't worry about it... there are plenty of other better things to worry about at this time of year.
Since someone else brought up the RS-485 spec, it should be noted that RS-485 technically requires a terminated line (which we aren't using). Any idea how many feet out of that 4000 we can really use before we should really terminate the last device?
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Pony_God
Senior Member Joined: 01 Sep 2008 Location: Naples, FL Online Status: Offline Posts: 551 |
Quote Reply Posted: 13 Nov 2008 at 9:46am |
I haven't measured, but I'm sure that I'm over 100' and havent seen any issues yet. |
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kennyz06
Newbie Joined: 05 May 2008 Location: Texas Online Status: Offline Posts: 24 |
Quote Reply Posted: 13 Nov 2008 at 9:21am |
I had runs of 100ft last year and had no issues....
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breakbenj
Pre-Order User Joined: 21 Dec 2007 Location: Georgia Online Status: Offline Posts: 102 |
Quote Reply Posted: 12 Nov 2008 at 10:18pm |
Thanks for everyones reply, I'm not sure exactly how long my runs will be but I'm sure it is under 60ft.
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Jeff
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Comporder1
DMX Joined: 11 Dec 2007 Location: Brookhaven, MS Online Status: Offline Posts: 163 |
Quote Reply Posted: 12 Nov 2008 at 10:05pm |
You have nothing to worry about. There is *NO* delay. The data on the CAT5 cables is moving at a rate of 200,000 km/sec. So even if you could have a delay, your cable would have to be 125,000 miles long (about 5 times around the equator) for 1 second of delay! Btw, the RS485 standard limits your cables to 4,000 feet ;) (I don't remember what the d-light/lor RS485 adaptor limitations are.) If you want to get real technical about it, worst case cenario, if you use a 4000 foot CAT5 cable, your delay would be .000006 seconds (or 6us)!
Edited by Comporder1 - 12 Nov 2008 at 10:09pm |
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ChrisL1976
Beta Testers Joined: 01 Sep 2008 Location: Kankakee, Ill Online Status: Offline Posts: 1341 |
Quote Reply Posted: 12 Nov 2008 at 9:03pm |
whats your longest run? I had 60' last year and no issues what so ever
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Chris
www.lightsonsixth.com |
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breakbenj
Pre-Order User Joined: 21 Dec 2007 Location: Georgia Online Status: Offline Posts: 102 |
Quote Reply Posted: 12 Nov 2008 at 8:30pm |
I'm using an FM transmitter also but all I have done so far is listen to the sequences without the lights going. I meant a delay from the sequence itself to the lights, I had heard that depending on the length of cords and cables you might experience delays.
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Jeff
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