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Cable type for keypad
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 Posted: Sunday Jan 19th, 2014 11:58 am
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gjb
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What type of cable do I need to wire a keypad to Comfort?
Cable shielded (S/UTP), pair shielded (STP), or both (S/STP)?
Does the shielding need to be terminated to common? At one end or at both?
Thanks.

Attachment: stp-udp.png (Downloaded 74 times)



 Posted: Sunday Jan 19th, 2014 12:26 pm
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juwi_uk
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STP

Last edited on Sunday Jan 19th, 2014 12:27 pm by juwi_uk



 Posted: Monday Jan 20th, 2014 04:25 pm
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wiredhome
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Also it is better if it is stranded
soild drawn cable tends to snap when terminated under screws
we use a belden equiv. of 9504 (i think that's the number, its a 4 pair screened cable) rather than cat5/6, its more flexible and easier to terminate in the keypad and panel



 Posted: Monday Jan 20th, 2014 07:09 pm
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A foil wrapped cable....,
You can get foil wrapped alarm cable or and FUTP CAT5 or 6.


We have come across many comfort installations with NO additional sheething on the keypad/doorphone, in a majority of cases there has been little or no effect on the quality of the voice.
I WOULD HOWEVER ALWAYS RECOMMEND THE USE OF A FOIL WRAPPED CABLE.



 Posted: Monday Jan 20th, 2014 07:18 pm
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juwi_uk
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BTW this was also asked at:
http://www.comfortforums.com/view_topic.php?id=1495&forum_id=1&highlight=STP

Last edited on Monday Jan 20th, 2014 07:19 pm by juwi_uk



 Posted: Monday Jan 20th, 2014 07:58 pm
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gjb
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Thanks for your responses.

I have read that with some types of cable, it's recommended to bond the insulation to ground. Does that apply in this instance?

My reason for asking is that I am currently testing a keypad with FTP cable (I bought the wrong one), and am hearing interference in the form of clicking from the keypad.

Last edited on Monday Jan 20th, 2014 08:25 pm by gjb



 Posted: Tuesday Jan 21st, 2014 08:25 am
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ident
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Yes it is best to connect the shield to ground on Comfort

You should also keep the keypad cable away from any noise source like mains cables

But what sort of clicking are you hearng? where could it be coming from



 Posted: Tuesday Jan 21st, 2014 01:39 pm
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gjb
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ident wrote: Yes it is best to connect the shield to ground on Comfort

You should also keep the keypad cable away from any noise source like mains cables

But what sort of clicking are you hearng? where could it be coming from

Thanks. I have ordered the proper STP cable, so will make sure this is connected to ground when I rewire it.
In the meantime, the FTP cable that I am currently using for testing is far away from any mains cables. The interference comes from the keypad speaker whenever it is active. I have attached a sound recording. It happens all of the time, but is best heard in isolation towards the end of the recording. I wonder whether it could be cross-talk between the pairs?

Attachment: comfort_interference.m4a.zip (Downloaded 10 times)



 Posted: Tuesday Jan 21st, 2014 05:05 pm
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ident
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I cannot play the file Error message says Windows Media Player does not support it or the file is damaged



 Posted: Tuesday Jan 21st, 2014 05:17 pm
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gjb
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ident wrote: I cannot play the file Error message says Windows Media Player does not support it or the file is damaged

It was recorded using my iPhone. It plays fine on my Mac.
On a PC, try opening it with VLC Media Player or iTunes.



 Posted: Tuesday Jan 21st, 2014 05:44 pm
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ident
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The sound worked with VLC media player worked
That is quite soft, it sounds like RS485 noise. Check that the RS485 bus is securely terminated on both ends. The bus can still work if  one wire is disconnected but may give noise. Does turning down the keypad volume reduce the noise?



 Posted: Tuesday Jan 21st, 2014 08:16 pm
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gjb
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ident wrote: The sound worked with VLC media player worked
That is quite soft, it sounds like RS485 noise. Check that the RS485 bus is securely terminated on both ends. The bus can still work if  one wire is disconnected but may give noise. Does turning down the keypad volume reduce the noise?


By RS485 bus, do you mean the KA/KB connections? I have just checked these at both ends and they are making good contact. I have also disconnected the UCMs so that the keypad is the only device using the bus, but that didn't make any difference.
The keypad volume does adjust the volume of the interference, but it is not linear. At 0%, it is barely audible; by around 30% the interference has reached it's maximum volume; increasing the volume further only affects the level of the voice, not the interference. Does that suggest where the problem might be?



 Posted: Wednesday Jan 22nd, 2014 06:37 am
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ident
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Yes, KA KB is t he rs485 bus
The noise is probably due to the interference from KAKB to the mic/voice signals

Make sure your KA/KB and MIC/VOICE are paired correctly in the CAT5
and the shield is grounded



 Posted: Wednesday Jan 22nd, 2014 01:15 pm
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gjb
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I'm going to rewire the keypad with STP (once the cable arrives), so will make sure that the shield is grounded. Hopefully that will solve the problem. Thanks.



 Posted: Monday Nov 21st, 2016 04:43 pm
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cgiltrow
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Hi,

Over and above the shielding, it is important to get the pairing right in order to get the benefit of the interference resilience that twisted pairs offer.

Am I correct in using the following pairs (for a keypad):

Pair 1: 12v+ and 12V-

Pair 2: KA and KB

Pair 3: Mic and 12V-

Pair 4: Voice and 12V-

Thanks,

Clinton.



 Posted: Monday Nov 21st, 2016 05:35 pm
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slychiu
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Pair 1: 12v+ and COM
Pair 2: KA and KB
Pair 3: Mic and 12V
Pair 4: Voice and COM


we normally recommend
12V/COM
KA/KB
Mic/Voice
Spare

But I think your way may even be better as Mic and voice are paired with  the power and return



 Posted: Tuesday Nov 22nd, 2016 09:43 am
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cgiltrow
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Thanks Chiu,

Can I just confirm (as you changed my post slightly), is it:

Pair 1: 12V and COM

Pair 2: KA and KB

Pair 3: Mic and COM (or MIC and 12V - as you showed in you last post)

Pair 4: Voice and COM

Clinton.



 Posted: Tuesday Nov 22nd, 2016 09:52 am
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slychiu
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MIC and COM
Voice and COM

should be best



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