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+--- Thread: Cable Lengths (/thread-1016.html)
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- rollem - 04-07-2008
Hi
I have been through the manuals and can\'t help but feel the answer to this is there looking me in the face! Does anyone know the max distances using CAT5 cable for door stations and keypads?
Thanks.
- admin - 04-08-2008
The Comfort bus is based on RS485 so in theory it can be more than 1 KM
However for keypads and door stations, it is advisable to keep it less than 100 meters due to the sensitivity of audio signals. Use Shielded CAT 5 cables. Also the extra length causes more signal delays which could mak it more difficult to tune the intercom to achieve higher volume without howling or positive feedback
- garym999 - 04-19-2008
Several issues here....
Comfort bus KA/KB (Differential)
This uses RS485 and so long cable lengths can be supported, 1km as mentioned. I have never tested this.
Comfort Audio (Single ended)
This would certainly start to deterioate over long distances. Depending on length try these steps...
1) Cat5 - Re-configure the wiring so that the mic runs down one pair and voice down the other. One wire of the pair would carry the signal the other would be grounded.
2) As above but use screened Cat5 (FTP)
3) Install a dedicated screened coaxial pair to carry the audio.
4) If the lengths are really long use Baulns to convert from Single ended to diferential signals. I have a gate phone runnig 1/2Km using this method.
Comfort Power
As soon as the lengths increase the voltage and current available will start to drop at the remote end. Double up pairs to decrease this, run dedicated power conductors or consider remote PSUs.
Also remember that if you are running long distances consider the enviromental issues, run cables in ducts, try and keep the moisture out or used external grade cable. Lightning storms can cause nasties.
- EOTB - 07-27-2008
Hi
Sorry to semi-hijack this old post.
I am about to start running the cabling for the alarm system. I noticed in the manuals it says to use shielded/foliled (S/FTP) CAT5e to the door phones and the control panels etc - especially over long distances etc.
The longest cable run in CAT5e I will be having is approx 15m. It will be passing mains power cabling on the way. Will I still require S/FTP for these short runs, or will normal UTP be OK.
If I do require S/FTP cable where do I terminate the shielding? I assume to the earth connector at both ends?
Thanks for any information.
Adam.
- slychiu - 07-28-2008
The more critical run will be for the Door stations and Keypads because of the sensitivity of the audio
If you are passing near Mains it may cause buzzing to be heard during the voice menu and intercom
It is safest to use FTP or STP and terminate shield at the controller end
Many people have got away with UTP if there is no mains cabling nearby
- garym999 - 07-28-2008
General guidelines...
- Never run small signal/data lines parrallel with mains/power cables unless a separation of 300m can be maintained.
- When crossing mains/cables do so at 90 degrees
- Do not use cable coax or shields as 0V power connections
- Only ground shields at one end preferably at Comfort end
KA/KB one pair
+ 12V one pair
MIC shared with 0V - one pair
Voice shared with 0V - one pair
- EOTB - 08-03-2008
Thats for your help.
Hopefully will be OK over the short distances. I may test with a length of CAT5e with a speaker and source at either end.
Cheers
Adam.
- garym999 - 08-03-2008
That will work. The problem might be interference from the mains cables when in situ and that might be harder to test long term.
- EOTB - 08-03-2008
Yeah - I will try and switch on equipment on the circuits around the cabling. I might have to use STP anyway as we are using low energy lights and I have heard that this can produce a lot of noise as they are basically flori\'s.
Speaking of which, as I am using low energy lighting, will the TWS modules still work - as in detect the current. I can find any specs on this in the manual?
Thanks
Adam.
- garym999 - 08-03-2008
The manual for the TWS is here. Look at page 2. Sensitivity is rated at 100mA so proably too high for a single CFL. A 11W one consumes about 50mA