Alarm Contact

[Melanie]

Most alarm systems I've come across have a series Resistor in each Sensor. Attempt to bypass the Sensor (with Darrels aligator clips) and you unbalance the circuit setting the Alarm off. But hey, who am I to comment... I'm not thirty yet!

[Pesticida]

Ok thanks people,now I know what i have to do.
I made a Security Software in Visual Basic,for the moment for 4 Alarm Contact.
I have work two week on this Software,the most lost time was on the PIC
controller.

Thanks !!!
Bye Pesti

[Normnet]

I think this was from Forrest Mims. Intelligent Alarm.

Alarm resisters of different values in series.
Each window/door if opened closes across a resistor?
Total resistance (Pic AD) indicates which resistor is shorted.
Even with combinations of resisters shorted it can be determined which windows are opened.
Tamper is if not one of the combinations.

Norm

[Luciano]

Hi,

What about an alarm system based on RS-485 supporting up to 32 devices (even 128)
with maximal network length of up to 1500m?

With the master PIC you could:

- Query the status of the slave PIC.
- Reset the alarm status of the slave PIC.
- Turn the light on and off inside the room via slave PIC.
- .....
- .....

Also with the VB program talking to the master PIC via RS-232 you could
dynamically define areas which are protected also during the day and monitor/log
the activity of each slave and and therefore know which window/door you will
have to check before you leave the building.
What about verify the temperature of the air-conditioning in the computer server room?
There are no limits here.....

Best regards,

Luciano
Star Trek Security Systems

[Pesticida]

Hi,
This is a very good Idea Luciano with Master and Slave ,
did you know where can I find Schemas about RS-485.

Bye Pesti.

[Luciano]

Do a search on this forum for "RS-485" or "RS485".

Luciano

[Pesticida]

Hi,
I found this schema I think this is ok?
Have anybody experience with RS 485 connections.

The Alarm Contact with the two resistors like on my Alarm Box works just fine.
I have now three states:Alarm,Normal,Sabotage.
Thanks People for the help!!!

I made that my Visual Basic Software send every second data to PIC and back,the Software saves the data (Contact States+Date+Time) on one file and then the Software read the data from the file and shown on the GUI,when the State is Normal I can reset the Alarm, and so on.
All is working very good but I must to expand the capability.
For the moment I can adjust the time interval,map load,save the Contact coordinates on the map,text for the contacts,pictures for the contacts,Port adjustment,Sound on Alarm.
I want to made this what Luciano mean with Master und Slave,any Slave Pic have a ID Adress and so on,I can adjust the adress with DIP switch.

Regard Pesti.