Ethernet Alarm

[Donny M. Carter]

I was looking on Planet Christmas forum and someone was selling this little alarm box that hooked between controllers. The post was by (lowinhz). I tried to copy the thread but it did not work. Does any one have any knowledge of how to build or how it works. I tried to also contact seller but no response. Thanks for any help.

[Guest guest]

What are you trying to monitor/alarm? Loss of controller communication?

I assume this is the post: http://forums.planetchristmas.com/showthread.php/36003-Alarm?highlight=ethernet+alarm

Looks like he's been trying to dump that thing for awhile..price has dropped 30%..

[ErnieHorning]

On all LOR boards except the older CTB-08, pins 1 & 2 pass through both RJ45 connectors. These two pins are normally not used for anything.

You would need to modify the cable going into the first controller so that the wires for pins 1 & 2 connect to your alarm. On the very last controller plug in a male RJ45 connector that has a single wire connected to both pins 1 & 2. This completes the loop. So now if any controller is unplugged, the loop is disconnected and the alarm sounds.

The alarm could be any alarm that sounds when the connection is broken. A simple alarm like this $10 one would work.

[Guest guest]

So that would verify continuity of the cable, assuming if that pair opens, you likely have a bigger break. Re-reading the original post from PC (always helps to do that first..), looks like this is all it is..continuity verification.

I had this wild vision of a device to sense something past that, i.e., loss of data communication due to a computer or controller lock up. That device, as described, definitely stops short of having that ability.

[Donny M. Carter]

Yes Don that is the post.
Thanks Ernie for the info, just what I was looking for.

[Donny M. Carter]

Don, I also thought it was very complicated. Now that the concept has been explained I will try to build something.

[bisquit476]

I bought one off of him last year, it worked good, checked the battery when I tore the display down, and it still set off the buzzer.

[Donny M. Carter]

Ernie would it be a simple wire hook up, or will i need relays. Any tips would be greatly appreciated.

[ErnieHorning]

DonFL wrote:

I had this wild vision of a device to sense something past that, i.e., loss of data communication due to a computer or controller lock up. That device, as described, definitely stops short of having that ability.

I know it’s been requested a few times but never implemented. I’m sure it’s not too difficult in software to find all controllers over the network, the hardware utility does it. Then if any unit ID is missing, it can sound an alarm, flash all channels, run another program, etc.

I'm assuming that there have not been enough request for this to spend any time on it.

[Guest guest]

Donny M. Carter wrote:

Ernie would it be a simple wire hook up, or will i need relays. Any tips would be greatly appreciated.

Depending on how elegant you want it, it could be as simple as a battery and a bulb, or a resistor and LED...when the light goes dark, means you have a break. If you want a sounder, you could use a relay, and put the sounder on the NC contacts, let the continuity with power source be what closes the relay and keeps it closed until you have an open somewhere in the cable. You could probably do it for 10 bucks, assuming you don't have any parts lying around.

[Donny M. Carter]

Perfect.. Thank You!

[ErnieHorning]

Donny, it’s very simple. You just need to bring out two wires going into the first controller (that go to the security system) and plug in the loop back connector into the last controller. All security systems that I know of connect everything in series and if any connection opens up, an alarm can sound.



You can make it as simple as turning on a light, sounding a horn, dialing a phone number or any number other things.

[Donny M. Carter]

Ernie< do I need to limit voltage? Still just trying to figure out the correct way to do what I want. I'm probably over thinking the whole thing. I just want to build something simple that makes noise when a controller is unplugged. Thanks for all the help.

[Max-Paul]

Ok here is one way of doing it. You will need a DC power supply that is the same voltage as a relay and a buzzer or sonalert.

Example: I took a length of Cat 5 and striped about 12" of jacket off of one end. I am using the orange and org/wht that usually go to pins 1&2. So I left these two long, and folded them back onto the cable. I trimmed all of the other wires to about 3/4" long. Arranged them in the proper order and installed the RJ-45 male connector. This is plugged into my USB to RS-485 converter. As mentioned before, run your comm cable to all of the other controllers. But on the last controller install a RJ-45 male connector on the out port. This connector need a single wire installed on pins 1 & 2. Now back at the first connector with the orange and org/wht. Take the orange wire and install it on the positive terminal of the power supply. Take the org/wht wire and install it on the relay coil. And connect a wire to the other relay coil terminal and run this back to the negative terminal of the power supply. Take a wire from the positive terminal on the power supply and connect it to the relays common contact terminal. Take a wire from the N.C. terminal of the relay and run it to the positive terminal of the buzzer or sonalert. Take a wire from the negative terminal of the buzzer or sonalert and connect it to the negative terminal of the power supply.

Very important: The power supply, relay coil and buzzer/sonalert all must be rated for the same voltage. I suggest that you use something rated at 24VDC due to the voltage drop that can occur

How it works, With a closed loop (all controllers present). Current leaves the P.S. and goes out on the Cat 5 cable orange wire. Goes into and back out of the controller onto the next cable. At the last controller it goes in and goes to the out connector. At this connector it is looped back at the RJ-45 male connector with the wire between the 1 and 2 pin. Now the current is on the org/wht wire heading back to the first connector that we made with the wires that where folded back onto the cable and is not connected to the relay. Current goes through the relay coil and back to the negative terminal on the P.S. This causes the relay to energize and open the N.C. (normally closed contacts). If the cable is broken, the current stops flowing through the coil of the relay. It de-energizes and closes the contacts. This now supplies power to the buzzer or sonalert.

Sorry for being long winded. But I hope this helps anyone wanting something simple but effective. This is only good for a circuit that does not use a comm circuit that does not use a splitter. Just a simple straight daisy chain circuit.

[Donny M. Carter]

Thank You, Thank You, Thank You Very Much!:cool::cool:

[Max-Paul]

Donny et all,

First I should have re-read my post. During the explaining of operation, I mistakenly used the word "not" when it should have read now. I am sure many of you will notice the typo and will be able to realize what I should have typed.

One thought, what ever relay you buy. Be sure to buy the smallest one you can get at the voltage rating you are using. Smaller relays require less current to operate. Less current demand will insure a lower voltage drop at the relay. Hard to explain to those of you who do not understand the relationship between wire size, its resistance over a given distance. And how this effects the voltage drop and how the current requirements of a device on the wire will eventually effect the voltage drop.

Sorry about any confusion the typo added to the concept.

[ErnieHorning]

This size relay that's needed on this application is very small since the current requirement is low. The kind that comes to mind is about the size of a sugar cube and is rated around 12 volts DC and less than .1 Amps.

This type is also very tolerant of voltage drop. These will typically pull-in at 75% of their rated voltage and once on will stay with only 25% of the rating or less.

For the supply, the smallest wall wart that you can find will probably still be way more than actually needed.

[ErnieHorning]

Double post. Too much caffeine!

[Donny M. Carter]

Just an update. My alarm works great! Built it for around $10
Thanks for all the help.:cool:

[Max-Paul]

Glad to hear that your alarm is working. Miracle that you could understand my weak attempt at describing how to do it.

Would you mind describing what you used for the P.S., relay and buzzer? Could be a learning experience for me and others.