5 actions with 1 reaction

[13Owen]

I work in the security industry and am servicing older alarm systems with
multiple alarm detector per alarm input. Nowadays we dont have a problem
with too many alarm detectors for the number of alarm inputs. We buy a 16
input panel and just keep adding 8 input expander cards until there are
enough inputs.

In the past most alarm panels had either 4 or 8 inputs and here in-lies my
problem. I have dozens of sites to service that have in excess of 100
detectors and only two or three alarm panels, usually 30 to 40 detectors per
panel. With the eighth input used for a key switch that leaves 7 inputs
divided by say 35 detectors leaving 5 detectors wired in series per input.

That is fine until there is an intermittent false alarm problem. WHICH !!!!
of the five or so detectors is the problem or has an envrionmental problem.

I have done things like short circuit one at a time until the problem goes
away which didn't work because the problem being intermittent when I got to
the last one it didn't play up. "Murphy's Law" Murphy is a SOD. So I hooked
them all together in series again and guess what? The thing played up again.
Also it may be over 100km to the site and the cost is too prohibitive to go
there half a dozen times also the level of security is tainted by having
multiple dectectors taken out over a long period of time.

It has been suggested to replace the detectors with ones that are less
likely to false alarm which gets expensive to through away four good
detectors just to find a faulty detector and you find that the problem was
the environment anyway and not the detectors. Or to rewire them so that they
are not is series but the sites are very large and there is not the inputs
spare anyway.
Or increase the size of the panel which would involve a total rewire and
upgrade and overhaul of the whole system costing in excess of $60,000.00 or
$100,000.00 to fix a $100.00 detector or even an envorinment problem for $0?

I tried with some success with universal wireless TX's and an 8 channel RX.
I connected a TX across each of the alarm detector output relays and wired
the RX output relays in series with the other alarm panel inputs. This
worked by having the false alarms appear on one of the other alarm sectors
and by going to the corresponding TX I was able to find the problem. This
involved only two visits to the site and the level of security was not
compromised. I was also able to monitor the wiring by joining the alarm
wires at each detector an monitoring that as well. Sounded good until the RX
would lock up or I had a problem with the distance from the TX back to the
RX.

There must be an electronic solution.

There is one pair of cables with 5 or 6 contacts in series.
Thats 5 or 6 actions for the 1 reaction.
How do you turn those 5 or 6 actions into 5 or 6 reactions.
Without major works.

Yes you would have to go the each detector and do something and that is OK.
Having a small device at each detector is OK. Having something small like a
resistor of a few small component that would fit inside the detector would
be better. There is 12 Volts available at the alarm panel and room to fit a
circuit board. This needs to work only when the alarm system is turned on.
There are lots of people in the building during the day. The results may be
record on or off site and viewed later. There is access to the key switch
input for switching purposes.

This has had me puzzled for years and I would love to beat it.



Owen
(remove "no-spam word" from e-mail to contact me)

 

[happyhobit]

Hi Owen,


For your application I’d build 5 or 6 battery powered, microcontroller based,
single input, Data Recorders.

Each one would have a running clock (synchronized to each other ) and record
the time of a contact opening is into EPROM.

After a fault, the recorders would be interrogated or collected, and their
EPROMS up-loaded to identify the fault location.


Size? 55mm X 35mm X 10mm 1000 hour battery life. (rechargeable Lithium
Ion) Hardware cost ? $20 (US) each

 

[happyhobit]

Hi Owen,

I may have over designed my original suggestion.

The simplest thing would be several 1-bit memories.

A 1-Bit memory would be a battery powered Flip-Flop connected across each
device, with an arming switch and an LED to indicate contact opening.

30 years ago I used a relay, with a holding contact, as a 1-Bit memory to
track down ‘Intermittent Interruptions’ in an Emergency Stop circuit in large
stamping presses.


Jay

 

[Terry Given]

Hi Owen,

I may have over designed my original suggestion.

The simplest thing would be several 1-bit memories.

A 1-Bit memory would be a battery powered Flip-Flop connected across each
device, with an arming switch and an LED to indicate contact opening.

30 years ago I used a relay, with a holding contact, as a 1-Bit memory to
track down ‘Intermittent Interruptions’ in an Emergency Stop circuit in large
stamping presses.


Jay

Now you're talking. I ROTFLMAO at the first suggestion, but this is very
good. a very simple and cheap single-event latch is of course a fuse - a low
current one could be arranged to blow when the detector output triggers. But
the self-latching relay is very good, and a visual indicator simplifies
things.

Cheers
Terry

 

[happyhobit]

Hi Terry,

Now you're talking. I ROTFLMAO at the first suggestion, but this is very
good. a very simple and cheap single-event latch is of course a fuse - a
low current one could be arranged to blow when the detector output
triggers. But the self-latching relay is very good, and a visual indicator
simplifies things.

IROTFLMAO? I beg your pardon. Quality is conformance to Specification.

If your trying to track multiple ‘actions’, some intentional and others
accidental, and tie the accidental ‘actions’ to a specific ‘reaction’ the
first solution will work. (And really wouldn't be that difficult to
implement)

If you’re trying to identify that a contact that is NEVER supposed to open,
has opened than solution #2 will work.


"There were two ways to do things: the simple way and the hard way, and a
surprisingly number of people preferred doing things the hard way. ", RUBE
GOLDBERG http://www.rube-goldberg.com/


P.S. My 30 year old example was using a manually latched relay, holding in
through one of its N.O. contacts.

If the E-Stop circuit opened, if only for a half-second, the relay would drop
out and 'remember' that power had been lost. By moving where the relay was
connected in the E-Stop circuit I could identify where the problem had
occurred.

These were 250 Ton automatic presses running 60 to 90 cycles per minute and
they shook a LOT.

I called that relay my 'Glitch Catcher' or 'Tattle-tail'.

 

[happyhobit]

P.S. My 30 year old example was using a manually latched relay, holding in
through one of its N.O. contacts.

No, I said that wrong.
The relay was electrically latched and manually engaged (I’d push the relay
in and the N.O. contact would close and hold it in.)



Jay

 

[JeffM]

intermittent false alarm problem

13Owen

What you seek already exists.
Someone in the alarm business should be aware of "Swinger detectors".
I'm thinking ADEMCO catalog.

 

[Tim Shoppa]

In the past most alarm panels had either 4 or 8 inputs and here in-lies my
problem. I have dozens of sites to service that have in excess of 100
detectors and only two or three alarm panels, usually 30 to 40 detectors per
panel. With the eighth input used for a key switch that leaves 7 inputs
divided by say 35 detectors leaving 5 detectors wired in series per input.

That is fine until there is an intermittent false alarm problem. WHICH !!!!
of the five or so detectors is the problem or has an envrionmental problem.

What's a typical current in each series chain? Probably something like 20 or
100mA, to get enough wetting current for the NC switch contacts.

If you put, in parallel with each detector, a small fuse (10mA), then that
fuse would blow when its detector opened. This would tell you which
detector in the chain was falsely triggering.

Now these very-low-current fuses aren't real cheap, but they are easily
wired in place with each detector. No firmware, no additional wiring.

Tim.

 

[Dave VanHorn]

What's a typical current in each series chain? Probably something like 20 or
100mA, to get enough wetting current for the NC switch contacts.

That may be part of the problem. Not enough wetting current in the loop.
BTDT.

 

[Terry Given]

Hi Terry,




IROTFLMAO? I beg your pardon. Quality is conformance to Specification.

If your trying to track multiple ‘actions’, some intentional and others
accidental, and tie the accidental ‘actions’ to a specific ‘reaction’ the
first solution will work. (And really wouldn't be that difficult to
implement)

If you’re trying to identify that a contact that is NEVER supposed to open,
has opened than solution #2 will work.


"There were two ways to do things: the simple way and the hard way, and a
surprisingly number of people preferred doing things the hard way. ", RUBE
GOLDBERG http://www.rube-goldberg.com/


P.S. My 30 year old example was using a manually latched relay, holding in
through one of its N.O. contacts.

If the E-Stop circuit opened, if only for a half-second, the relay would drop
out and 'remember' that power had been lost. By moving where the relay was
connected in the E-Stop circuit I could identify where the problem had
occurred.

These were 250 Ton automatic presses running 60 to 90 cycles per minute and
they shook a LOT.

I called that relay my 'Glitch Catcher' or 'Tattle-tail'.

In the context of the original post, solution #1 is breaking eggs with a
bulldozer you have to assemble yourself. the latching relay is nice though -
and as you say, found inside most E-stop circuits. If you happen to have a
tame micro guy around who is quick and good, solution #1 becomes feasible,
otherwise it aint - when choosing a stranger to implement a microcontroller
project, Murphy indicates you will pick the most dumb-assed moron in
existence, who will spend well over the budget to produce rubbish code thats
very late and doesnt work properly

(if the OP was able to do it himself he would have by now - IME micro guys
love throwing 8-pin cpus at problems - he says having finished just such a
little design that someone else is writing the code for)

Cheers
Terry

 

[happyhobit]

In the context of the original post, solution #1 is breaking eggs with a
bulldozer you have to assemble yourself. the latching relay is nice though
- and as you say, found inside most E-stop circuits. If you happen to have
a tame micro guy around who is quick and good, solution #1 becomes
feasible, otherwise it aint - when choosing a stranger to implement a
microcontroller project, Murphy indicates you will pick the most
dumb-assed moron in existence, who will spend well over the budget to
produce rubbish code thats very late and doesnt work properly

(if the OP was able to do it himself he would have by now - IME micro guys
love throwing 8-pin cpus at problems - he says having finished just such a
little design that someone else is writing the code for)

I guess you’re right Terry.

I’ve been playing with micros too long, 30 years and I’ve lost some
perspective.

But, I still like the microcontroller solution. : )

 

[N. Thornton]

In the past most alarm panels had either 4 or 8 inputs and here in-lies my
problem. I have dozens of sites to service that have in excess of 100
detectors and only two or three alarm panels, usually 30 to 40 detectors per
panel. With the eighth input used for a key switch that leaves 7 inputs
divided by say 35 detectors leaving 5 detectors wired in series per input.

That is fine until there is an intermittent false alarm problem. WHICH !!!!
of the five or so detectors is the problem or has an envrionmental problem.

from what you say it sounds as if replacing all 5 detectors might be
the cheapest option. You could plug them into a test rig at home which
will find the bad one. Then either sling them or return them at next
service. Your temp replacements then get used multiple times, making
cost per go low.

Its not quite what you wanted, I know. Seems this approach is an
inherent consequence of using this type of setup in the first place.
The setup basically eliminates other options, short of modifying the
setup at each detector - but if you do that you might as well just
replace the detectors with temp ones.


Regards, NT

 

[Terry Given]

I guess you’re right Terry.

I’ve been playing with micros too long, 30 years and I’ve lost some
perspective.

But, I still like the microcontroller solution. : )

turn it into a product, market it to the security industry as a tech tool.
yay for 8-pin 8051s

Cheers
Terry

 

[Terry Given]

from what you say it sounds as if replacing all 5 detectors might be
the cheapest option. You could plug them into a test rig at home which
will find the bad one. Then either sling them or return them at next
service. Your temp replacements then get used multiple times, making
cost per go low.

Its not quite what you wanted, I know. Seems this approach is an
inherent consequence of using this type of setup in the first place.
The setup basically eliminates other options, short of modifying the
setup at each detector - but if you do that you might as well just
replace the detectors with temp ones.


Regards, NT

whereupon it turns out to be a cable problem - bloody murphy.

Cheers
Terry