M1G Analog Inputs

[VE9PTR]

Can someone please explain how I can 'input' a 5v analog signal into a zone? I have a 5v signal (from an LED on a garage door monitor) that I would like to use, but rather than put a relay in, I think I can use the analog voltage value as my trigger. I see in the rules how they are applied, but I cannot find in any manuals or online how to actually connect a voltage input. Simply applying it accross the Com/Zone terminals seems to be what's implied.


Thanks in advance!
Pete

 

[signal15]

Can someone please explain how I can 'input' a 5v analog signal into a zone? I have a 5v signal (from an LED on a garage door monitor) that I would like to use, but rather than put a relay in, I think I can use the analog voltage value as my trigger. I see in the rules how they are applied, but I cannot find in any manuals or online how to actually connect a voltage input. Simply applying it accross the Com/Zone terminals seems to be what's implied.


Thanks in advance!
Pete

Why not get a low current 5V relay and connect it to an input? Then it's either closed or open. No voltage monitoring required. I think you can also use a transistor as a gate, but you'd have to look up how to do it. I was playing around with this for a low salt light monitor on my water softener last year, but the light blinks, so it was causing problems for me.

 

[electron]

The M1 uses 12VDC. I don't see how you could make this work without a relay or CdS photocell monitoring the LED.

 

[BraveSirRobbin]

Quick reply as I'm heading for work...

There are pros and cons with the analog input on the Elk. You could directly hook the five volt supply and calculate the bit setting you would see with the 8-bit analog to digital converter using 12 volts as the max input (see my Guide on Analog to Digital Converters).

The problem is the Elk is made for open collector inputs and they have a 'pull-up' resistor that could interfere with an analog input that does not have the sufficient 'drive' to overcome this resistance.

You could simply try it, set the input as an analog setting, then see the value in the 'panel' on the RP software setting. Be aware though that if it is hooked into anything 'sensitive' on your end, it may possibly damage the hardware (it probably will not, but have to put this disclaimer out there since I don't know all the details).

Another problem is if this is on an extension I/O I believe the inputs will not update for 30 seconds or so, unless they received a significant change in input. I can't remember the details on this (getting old) as it has been several years since I played around with this. I'm sure I did a post or two on analog inputs not updating (search for my nick on keywords).

The thing I would probably do is what Dan stated (using a CdS photocell). I have a circuit that would work using a transistor that you could connect directly to the Elk (played around with this circuit to originally trigger a DS10a, and it worked well at is had trigger 'adjustably' based on the LED light level). I'll probably do a detailed 'how-to' on this when I get some time.

Later,

BSR

 

[BraveSirRobbin]

Why not get a low current 5V relay and connect it to an input? Then it's either closed or open. No voltage monitoring required. I think you can also use a transistor as a gate, but you'd have to look up how to do it. I was playing around with this for a low salt light monitor on my water softener last year, but the light blinks, so it was causing problems for me.

You could wire a 'one-shot' or maybe a cap that would charge to overcome this. If this is a monitor though, why not just 'trigger' an event on a change and forget about future notifications (i.e. once a signal was received, you know the salt is low and further responses are not needed until you 'reset' a flag after filling the softner?).

As I stated above, I do have a circuit that will work with a DS10a and even made it so it can 'piggy back' on that unit so you have an 'all in one' device with no batteries external to the DS10a and completely portable.

 

[Mike_]

Hi Pete,

I have done what you're trying to do. If you're trying to monitor a garage door, open or closed, I suggest that you use a magnetic reed switch and give it a zone, this is usually the correct and elegant solution.

So you have a LED that you want to use to trigger a zone and you have measured five volts at the LED.

You can buy a cheap, 5V relay but it probably wont work at the current available to a LED. You can look for in-line resistors on the circuit and get to the current before it's reduced by resistors and then drive the relay. This isn't a great solution but life is short and it's ok.

If you just have the LED and nothing else to work on...

Is the LED positive (usually is), or negative switched? Does a + or - 5V activate the LED? Is + or - always on, usually -.

If -. Power your garage door monitor so negative is shared with the ELK. Power it from the ELK or just share negative on the 5v circuit.

Take the switched power from the LED and insert it into your zone on the ELK and it works.


Zone = type 2.


With a TS7805 voltage regulator you can attach all sorts of stuff to an ELK.

Best wishes and good luck,

Mike

 

[Lagerhead]

With a TS7805 voltage regulator you can attach all sorts of stuff to an ELK.

Really? Please post a schematic for a typical application along with an explanation of the method. A general-purpose analog interface for the M1 would be most welcome.

 

[linuxha]

Why not get a low current 5V relay and connect it to an input? Then it's either closed or open. No voltage monitoring required. I think you can also use a transistor as a gate, but you'd have to look up how to do it. I was playing around with this for a low salt light monitor on my water softener last year, but the light blinks, so it was causing problems for me.

Signal15, you could have used a 555 or a cheap micro to send the signal to the Elk. The TI MSP430s are cheap. Simple set a timer once you receive a voltage and set the timer longer than the cycle time of the on/off period and check for a high/low or low/high and reset the timer. If the timer goes off drop the signal to 0. Does that make sense?

 

[linuxha]

Really? Please post a schematic for a typical application along with an explanation of the method. A general-purpose analog interface for the M1 would be most welcome.

Lagerhead, I'll take a guess here that Mike_ is referencing the 7805 as just a voltage regulator for handling the 12v from the Elk. I haven't had time to really take a look at how to build external 'conditioning' circuits but it shouldn't be too difficult. I have a ton of tiny processors (the MSP430 which are only a couple of dollars) that I can do all sorts of magic with. Of course I need to work with lesser voltages and bring them up accordingly.

 

[Lagerhead]

Lagerhead, I'll take a guess here that Mike_ is referencing the 7805 as just a voltage regulator for handling the 12v from the Elk. I haven't had time to really take a look at how to build external 'conditioning' circuits but it shouldn't be too difficult. I have a ton of tiny processors (the MSP430 which are only a couple of dollars) that I can do all sorts of magic with. Of course I need to work with lesser voltages and bring them up accordingly.

Ya, agreed -- a 555 configured as a one-shot, a small relay, a transistor interface, optoisolators -- these are good solutions for binary on-off signaling. And this is what the OP seeks.

But, how to handle varying analog signals on an M1 input has been extensively investigated and discussed here, without a simple, reliable all-purpose solution. AFAIK.

 

[Monk]

I use 12V DC as a zone input and it works very well.
5 V may not be enough to turn the zone not secure but might be worth a try, and of course YMMV. Will try it later if I get a chance.

http://www.cocoontech.com/forums/index.php?showtopic=17126&st=0&p=145463&#entry145463

 

[Monk]

OK - I had to try - Spent about an hour with varying voltages and 2 different resistor values - The goal was to allow a 5V input to cause a zone violation. My result is the opinion that this method cannot be used (reliably) with an applied voltage of less than 12V.

I use 12V DC as a zone input and it works very well.
5 V may not be enough to turn the zone not secure but might be worth a try, and of course YMMV. Will try it later if I get a chance.

http://www.cocoontec...63

 

[Mike_]

Hi Lagerhead,

A TS7805 is a voltage regulator that converts the ELK 12v into 5v. It's a cheap component with three legs, hold it so the writing is facing you, left leg goes to 12v+, middle leg is ground, right leg gives you +5v.

An example application of no particular merit;

Go out and buy a few Philips 'Spot on', battery operated infra red controlled led lights for three dollars each, modify them and power them with a TS7805 (they need 5v). These sensors serve no security purpose. Find the switched voltage from the 'Spot on', feed it to the ELK, and it works (for me). I got some of these lights for something completely different but wanted a motion detector in my closet / wardrobe, I could have installed a new sensor but it was snowing, I had time on my hands and gave it a try, it works. Cost was four Euro and it passed a dull moment.

I don't think of this as a general purpose analogue interface, the ELK manual mentions that zones are polarised. This is expected functionality.

 

[Mike_]

Hi Monk,

I can grab my multi meter and verify exactly what I have done, what would you like me to measure? This works for me every time.

 

[Monk]

Hi Monk,

I can grab my multi meter and verify exactly what I have done, what would you like me to measure? This works for me every time.

What is the exact voltage that you are supplying the Elk Zone? How exactly is the zone setup? The method I described uses an 2200 eol resistor with the zone set for EOL supervision.