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Author Topic: Blackbox Switches for Cobranet (was: equipment mounted in ceiling spaces)  (Read 7338 times)

Jason Lavoie

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I have a situation where I'm running Cobranet from rack to rack and it may be a bit over the 100m maximum length and the only option seems to be to put a switch somewhere in between.
the only location that will work is in a drop ceiling air plenum space. is there any way to install a hub in a ceiling that won't violate fire regulations?

any cobranet recommended hubs that are nice and small and can be installed right in a pull box?

I wish there was a better option, but it seems this is the only place I can put it.
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Phil LaDue

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Don Boone

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Re: equipment mounted in ceiling spaces
« Reply #2 on: July 04, 2007, 09:34:27 pm »

Chief also has some plenum boxes but the issue is putting a heat producing device in a sealed box. Not a good idea.
Extron has plenum rated audio amplifiers that don't require an enclosure, so they breath free without having to have a sweat chamber box.

We need a plenum rated switch.

Don
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Ron Hebbard

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Re: equipment mounted in ceiling spaces
« Reply #3 on: July 04, 2007, 11:33:31 pm »

Jason Lavoie wrote on Thu, 05 July 2007 01:23


I have a situation where I'm running Cobranet from rack to rack and it may be a bit over the 100m maximum length and the only option seems to be to put a switch somewhere in between.
the only location that will work is in a drop ceiling air plenum space. is there any way to install a hub in a ceiling that won't violate fire regulations?

any cobranet recommended hubs that are nice and small and can be installed right in a pull box?

I wish there was a better option, but it seems this is the only place I can put it.


Hello Jason;

This may be a little rude but it's a methodology that's worked for me many times in the past.

When companies state suggested maximum cable runs they play it safe.

Measure the length you require, triple it and run a few tests.
If it works error free, install your "bit over the 100m maximum length" and sleep well.

If the triple length doesn't work, try a double length.
If the double length works, great, if not try 150m.

You've got the idea.  
Don't send out anything that's barely shy of the ratty edge but if it works reliably at 3x, 2x or 1.5x the length you need you're probably safe to go with it.

Back in my computer controlled a/c servo drive days, I found I could run RS-232 75' and resolver cable 200'.
The IT folks were telling us that 25' was the max for serial and the servo drive manufacturers were telling us that 40' was their absolute maximum length for resolver cables but only when ran in dedicated conduits.

When we were shipping a/c servos to Germany for 'Tommy', all of our drive cables were off the shelf grey vinyl jacketed control cables.
We'd typically have a 12/4 shielded motor cable, a double shielded resolver cable, a 16/2 shielded DC brake cable and an 18/4or5 shielded hard limit cable bundled together with a few wraps of electrical tape every 2 or 3 feet and no conduit in sight.

Prior to 'Tommy' Frankfurt, our longest cables were 100'.
When we needed 150' and 200' cables for Germany, we took full 1,000' put-ups and connectorized both ends for testing.
We found 1,000' was pretty ratty, pardon the technical word, but cutting the 1,000' in half to 500' seemed to work pretty well as far as we could tell by test running the rig in the shop.

After that, we sent the 200' lengths to Frankfurt and figured we'd be safe to send out anything up to 300' if / when the need were to arise.

Bottom Line:  Don't believe all you read, conduct your own exhaustive tests and form your own conclusions.

Toodleoo!
Ron Hebbard
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Jason Lavoie

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Re: equipment mounted in ceiling spaces
« Reply #4 on: July 04, 2007, 11:42:06 pm »

I was ready to try pushing the limits of cobranet, but a few things have me scared away from that.

number one is that the 100m limit is imposed by the computer industry, who can afford a few errors and dropped packets here and there, so if they could go over 100m without too much loss they probably would (and I haven't found many hits on the web of people recommending it)
With cobranet (correct me if I'm wrong) even a few errors could be pretty bad right?)

add to that the fact that 120m or more of cat5 strewn around my shop could behave very differently once it is installed and in a different environment

and if I do get it in and there's a problem, it'll be too late to ask for the necessary stopover point.

Jason
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John Birchman, CTS

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Re: equipment mounted in ceiling spaces
« Reply #5 on: July 04, 2007, 11:58:40 pm »

EIA 568 limits UTP copper cabling to maximum distance of 100 meters (328 feet). 90 meters of cable plus 10 meters of patch cord split between both ends.

If it is over the distance for copper, and putting a switch in the ceiling looks to be problematic, you should look at running fiber instead of copper, and put in media converters at each end.

John
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John Birchman, CTS
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JRB Technical
Lake Buena Vista, FL

Ron Hebbard

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Re: equipment mounted in ceiling spaces
« Reply #6 on: July 05, 2007, 12:01:12 am »

Jason Lavoie wrote on Thu, 05 July 2007 04:42

I was ready to try pushing the limits of cobranet, but a few things have me scared away from that.

number one is that the 100m limit is imposed by the computer industry, who can afford a few errors and dropped packets here and there, so if they could go over 100m without too much loss they probably would (and I haven't found many hits on the web of people recommending it)
With cobranet (correct me if I'm wrong) even a few errors could be pretty bad right?)

add to that the fact that 120m or more of cat5 strewn around my shop could behave very differently once it is installed and in a different environment

and if I do get it in and there's a problem, it'll be too late to ask for the necessary stopover point.

Jason


Hi again Jason;

Let me give this one last kick but only you know your situation and comfort level.

If you need 120m, test 360m and 240m.
Run it around your shop, take a couple of passes around serious power transformers and a couple of passes around your welders if you have some.
If things appear to be working but you're still concerned, install an accessable pull-box and route your cable, un-cut, through it.  Be sure to have power provided in / near your pull-box just in case.
Access could be via a proper, hinged, access door or by temporarily removing a fluorescent fixture to reach your pull-box.
Your pull box could be something standard with it's cover plate replaced by a piece of expanded metal / speaker grille material.
The box could be mounted on edge so as to put the grille on a side to lessen dust accumulation.

If you opt to play the 'push the limits' game, either play until you find where the ratty edge is or prove to your self that triple your required length works adequately.

I'll go 'way now.

Toodleoo!
Ron Hebbard
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Austin Parker

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Re: equipment mounted in ceiling spaces
« Reply #7 on: July 08, 2007, 06:18:01 pm »

In the ceiling??

Service access? fire protection? ventilation?
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Austin Parker

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Robert Sims

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Re: equipment mounted in ceiling spaces
« Reply #8 on: July 08, 2007, 07:36:51 pm »

Jason,
You may want to look at a conversion from copper to fiber back to copper to get you the distance you need. Attached is an inexpensive stand alone solution.

http://www.milan.com/TransitionNetworks/Products2/Family.asp x?Name=SGFEB101x-100
http://www.blackbox.com/Catalog/Detail.aspx?cid=308,1416,149 9&mid=4715

Many versions and costs.

Just another option.

Robert
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Robert Sims

Jason Lavoie

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Re: equipment mounted in ceiling spaces
« Reply #9 on: July 09, 2007, 11:56:44 am »

the blackbox converter just might do it. since it has an integrated switch with two UTP ports on each end I won't need a switch on top of the fiber link, and I won't have to put in two fiber links (original setup would have required at least one switch and two fiber links or two switches and a fiber link)

and although it might come in a bit more expensive to go with fiber it means I won't have to change any conduits or as for power at a stopover point.

thanks for the tip. anyone know if they have a reseller in Canada? and where is the best place to get pre-terminated fiber?

Jason
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