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Thread: NX4 Help - A Few Questions

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    Junior Member the_scotsman's Avatar
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    Default NX4 Help - A Few Questions

    I have a Networx NX4 that I asked about a number of years ago on the forums ().

    Seems I have the NX8 and I can do zone doubling. I never did get around to doing any more with it, until now.

    Currently I only have 3 PIRs connected. I want to add sensors to 2 patio doors, and front and back door. How does the zone doubling work? I assume I can literally just wire up 2 sensors to the one input on the motherboard?

    Are the door sensors generic? Can I use any reed sensor? Any suggestions for a reasonably cheap sensor to use?

    Also, I have a small dog, and want to be able to set the alarm with no worry about the dog triggering a PIR. Any suggestions on pet friendly PIRs that won't break the bank?


    One other thing that's bugging me. I want to know how long the alarm will sound when it's triggered. I can't find this documented anywhere. I'd hate to be at work and have the alarm trigger, scaring the heck out of the dog, and not being able to get home and turn it off.

    Thanks for any help



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    To do what you want you'll need to be able to get into programming to enable zone doubling. Zone inputs 1-4 are zones 1-4 when using a 3k3 eol and are zones 5-8 when using a 6k8 eol. PIRs and reeds are generic and not brand specific. The difference between a cheap reed & an expensive reed will be a dollar or two , hardly worth the bother. Most PIR manufacturers will offer a pet PIR , everyone will have their own prefference - I like the Bosch stuff. The siren will sound for whatever it has been programmed for. The easiest way to determine this is to set it off and watch the watch.

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    Quote Originally Posted by watchdog View Post
    To do what you want you'll need to be able to get into programming to enable zone doubling. Zone inputs 1-4 are zones 1-4 when using a 3k3 eol and are zones 5-8 when using a 6k8 eol. PIRs and reeds are generic and not brand specific. The difference between a cheap reed & an expensive reed will be a dollar or two , hardly worth the bother. Most PIR manufacturers will offer a pet PIR , everyone will have their own prefference - I like the Bosch stuff. The siren will sound for whatever it has been programmed for. The easiest way to determine this is to set it off and watch the watch.
    So where can I find how to enable to double zoning? Programming I can do...just need a point in the right direction as to what needs done. How does the connecting up work if there are only connnections on the motherboard for 4 zones?

    Thanks for the info regarding sensors. Any good place to find a selection? Any common websites people use?

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    Hate to be a pedant but the resistor values are 3k74 for zones 1 to 4 and 6k98 for 5 to 8. You may get away with leaving the 3k3s for the lower zones but you're leaving yourself open to higher risk of false alarms.

    Zones 5 to 8 are connected in parallel to zones 1 to 4 on the same terminals. The different value resistors are used to determine the active zone. This only works with NC devices though. If you have an NO device such as a smoke detector, you'll trigger both the upper and lower zone at once.

    As for programming, zone doubling is enabled in Feature 22, segment 5 and enabling option 2. Your siren timer is feature 25, option 5 with the siren time displayed in minutes (binary)
    Last edited by Drift; 09-02-13 at 10:29 AM.

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    Quote Originally Posted by the_scotsman View Post
    I have a Networx NX4
    Quote Originally Posted by watchdog View Post
    To do what you want you'll need to be able to get into programming to enable zone doubling. Zone inputs 1-4 are zones 1-4 when using a 3k3 eol and are zones 5-8 when using a 6k8 eol.
    Watchdog,

    I trust you made an honest mistake, and are not trying to lead to OP astray so he ends up having to call a tech out anyway to sort out the mess he is about to get himself into. The Bosch panels use 3k3 EOL for non zone-doubling and 3k3/6k8 for zone doubling, whereas the Hills NX panels use 3k3 for non zone-doubling and 3k74/6k98 for zone doubling (who the hell picked those values???!!!). One complication this presents is that you have to find and replace all the low-zone EOLs when converting an NX panel to zone doubling. I've also found that the NX is very fussy about the EOL value - I had a site recently where someone must have done exactly what the OP wants to do, and added a 3k74 resistor in series with an existing 3k74 on a low zone, to convert it to a high zone. The zone was randomly false-alarming and it took me a while to figure out what was going on. Even though 2 x 3k74 equals 7k48, which is close to 6k98, it must have been on the edge of the tolerance limit - enough to drift randomly and cause the false alarms. I fitted a single 6k98 and problem fixed.

    Back to the OP: Scotsman, there is a diagram in the front of the NX installation manual detailing how to zone-double. However, as you can see from my comments above, there is a fair bit involved and you are probably better-off calling a tech experienced with NX panels.

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    Well unless things have changed the resistors supplied with the NX panel are of 10% tolerance. So the 3k74 could be anywhere from 3k66 to 4k15 and the 6k98 could be from 6k28 to 7k68. This is the resistor alone and doesn't take into account variations caused by temperature or cabling length. The panel design allows for variations such as these and 3k3 / 6k8 will work just fine. Sure it's better to use the specified resistors as they are probably around the centre tolerance value.
    The example I gave was for explanation purposes only and I was certain some pedantic person would show their knowledge.

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    Quote Originally Posted by watchdog View Post
    Well unless things have changed the resistors supplied with the NX panel are of 10% tolerance. So the 3k74 could be anywhere from 3k66 to 4k15 and the 6k98 could be from 6k28 to 7k68
    I've just pulled out my stash of NX resistors and had a look (under a magnifying glass, to be sure) - the 3k74 is orange-purple-yellow-brown-brown and the 6k98 is blue-white-grey-brown-brown. In my book, the brown on the end represents a 1% tolerance, not 10%. So these values must be fairly critical, otherwise why would the panel designers specify resistor values to 2 decimal places? I stand by my previous example of why the correct EOL resistors supplied with the panel must be used, depending on the application (zone doubling or non zone doubling). Also, sorry to be pedantic (again), but your example above is partly wrong: 3k74 - 10% = 3k37 (rounded down) not 3k66, and 3k74 + 10% = 4k11 (rounded down) not 4k15. The other two values are OK.

    Quote Originally Posted by watchdog View Post
    I was certain some pedantic person would show their knowledge.
    I'll take that as a back-handed compliment.
    Last edited by alarmman; 09-02-13 at 08:24 PM.

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    Quote Originally Posted by alarmman View Post
    I've just pulled out my stash of NX resistors and had a look (under a magnifying glass, to be sure) - the 3k74 is orange-purple-yellow-brown-brown and the 6k98 is blue-white-grey-brown-brown. In my book, the brown on the end represents a 1% tolerance, not 10%. So these values must be fairly critical, otherwise why would the panel designers specify resistor values to 2 decimal places? I stand by my previous example of why the correct EOL resistors supplied with the panel must be used, depending on the application (zone doubling or non zone doubling). Also, sorry to be pedantic (again), but your example above is partly wrong: 3k74 - 10% = 3k37 (rounded down) not 3k66, and 3k74 + 10% = 4k11 (rounded down) not 4k15. The other two values are OK.
    Obviously to capture a market. Given that 7x.020 cable has a resistance of about 0.1^/m & supposing a cable length of 20m (40m return) that will give a cable resistance of about 4^. Also given that most PIRs have an inbuilt (about) 47^ resistor in series with the NC contacts that will give you a total (excess) resistance of maybe 55 ^. Add to that resistive variances due to temperature (say 5^) and we have a variance of 60^ before we consider the 1% tolerance of the resistor which will be 69.8^ for the 6k98. Total variation could be up to 120^. ie 1.72% of the 6k98 eol. That is getting close to double the 1% tolerance you insist is fairly critical. So how critical is it? A simple bench test causes a 3k74 zone to trigger at 3k1 and 4k2 while a 6k98 zone triggers at 6k5 and 7k4. It is obvious that that the panel design will have to allow for all the variables of external cabling possibilities if they want it to be stable so a design tolerence of 1% would be rediculous.

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    Quote Originally Posted by watchdog View Post
    Obviously to capture a market.
    This hasn't stopped me at times converting an NX site to a Bosch site (my panel of choice). I've had to find and replace all the 3k74 and 6k98 EOLs with 3k3 and 6k8 resistors.

    Quote Originally Posted by watchdog View Post
    That is getting close to double the 1% tolerance you insist is fairly critical.
    I'm not insisting anything. I'm only stating what I experience and have to deal with in the "real-world". Just because the NX panel designers have specified 1% resistors, doesn't mean that the zone input resistance tolerance is 1%, as you have found in your bench testing. In fact, your testing has found that a zone sealed with 6k98 will trip at an upper limit of 7k4 (an increase of 5.8%). If you refer to my earlier post, I experienced a high zone sealed with 7k48 (+ or - the 1% resistor tolerance, plus the external resistances you mentioned) randomly tripping the zone. This is right on your observed upper limit, and the tolerance variations in this case were probably enough at times (eg on a hot day) to exceed the zone upper threshold and trip the zone. I rest my case, your Honour.

    Again, I stand by my earlier statement - use the EOL resistors that come in the box and the panel was designed for.

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    There is a big difference between knowing what your doing and doing what you know.

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