Independent 12V Power Supply for Elk M1 485 Bus

I am putting together an Elk M1G system that will likely have many (30+ and growing) relays powered/triggered at the same time.

I was wondering if, to provide a more consistant and reliable power supply to the 485 bus, I could wire an independent 12V power supply into the 485 bus. My thought would be to use an Elk PS212 and use the two 485 signal wires from the M1G to the first card on the bus but use the PS212 to provide power to the first card and down the line.

Any thoughts would be greatly appreciated.

Thanks.
 
You can definitely do this. Make sure you "common" the negatives of the extra supply and the M1 supply voltage together.

Edit:
Here is another post that goes in to a bit more detail.


http://www.cocoontech.com/forums/index.php?showtopic=8686&st=0&p=90117&hl=+common%20+negatives&fromsearch=1&#entry90117
 
That's what those supplies are for, but not for powering the 485 bus, just system peripherals, anything that draws power, including keypads. The 485 bus still has the same limits as before.

If you wire the 212S as labelled, it's impossible to not share a common negative.
 
You can definitely do this. Make sure you "common" the negatives of the extra supply and the M1 supply voltage together.

Edit:
Here is another post that goes in to a bit more detail.


http://www.cocoontech.com/forums/index.php?showtopic=8686&st=0&p=90117&hl=+common%20+negatives&fromsearch=1&#entry90117

By running a single wire from the negative of the hub(which will also have the negative from the 212) to the negative of the bus on the M1?

Althought I wrote that I would place the PS212 between the M1 and the first bus device, I can place the PS212 between the M1 and the Hub so that if I add additional runs, I dont have to worry about rewiring the 12V power to the new runs. Once wired to the hub, all the legs will be powered by the PS212.
 
The 212 is wired like a keypad without the positive connection.

You'll still need to consider the overall current draw. Knowing the details about your potential install, you're looking at 1.140A being drawn by the relays alone, not counting 160mA for each keypad and any other ancillary devices connected to the supply.
 
I'm not sure I'm following DEL's comments... What you're trying to do with the aux. power supplies is exactly what they're intended for to solve the problem you're looking at - power draw on the overall bus (and/or powering accessories).

If you look at the installation guide for the P212S, there are specific installation notes for using the P212S to boost the databus.

Here is an excerpt:
* * Red Data Bus Wire - Positive (+): This wire is not actually needed as the P212S is a power supply. An isolated screw terminal marked "Spare" is provided for parking (terminating) this wire or for splicing with another cable if the bus is continuing on. The important point is that the P212S ONLY NEEDS THREE (3) connections to the M1 Data Bus, Negative (-), Data A, and Data B.


CAUTION: DO NOT connect the Positive (+) wires of multiple power supplies together! It is OK to connect all Negative (-) wires together, as this will assure the entire system has a common reference to Negative. 12 V POS and NEG Outputs:

These two (2) terminals may be used for powering motion sensors, zone expanders, etc., or to extend "boost" power on the data bus outgoing from the P212S. DO NOT connect the incoming data bus Positive (+) RED wire as this would result in unsafe backfeeding of power to previous devices/sources. See caution above. We recommend terminating or "parking" the Positive (+) RED wire of the incoming data bus to the terminal marked "Spare". Data bus devices prior to the P212S will be powered by the previous power supply, and devices after the P212S will be powered by the P212S. In the case of multiple P212S Supplies, this procedure can be repeated up to the maximum distance (4,000 feet) of the M1 data bus.


Since you can't access that portion of the site (only available to dealers or owners) I'll PM a copy to you.

Based on that, your downline expanders will be pulling off the auxiliary supply, not the Elk's main supply. You can continue to add more of these power supplies to handle anything you attach to the M1. Of course you want to make sure no single power branch exceeds what its's rated for.
 

It seems to me that doing this is way overkill and you might want to go back a revisit your requirements. If you indeed need to have 30 relays on at the same time, and your calculations indicate that you need this many relays, and that that requires more power than the bus can handle, then I would think it would be easier to just cascade your relays, have an elk relay trigger another relay that can handle all the circuits you need on at one time. Or alternatively breaking out the 120v side instead of the LV side of your lights, etc.

I would reserve an external power supply to powering your zones if needed as that is easier to break out, than trying to power the bus. If you try to add too much power to the bus you have to start considering if all the devices, wiring, etc are engineered to handle that.
 
I'm not sure I'm following DEL's comments... What you're trying to do with the aux. power supplies is exactly what they're intended for to solve the problem you're looking at - power draw on the overall bus (and/or powering accessories).

If you look at the installation guide for the P212S, there are specific installation notes for using the P212S to boost the databus.

Here is an excerpt:


Since you can't access that portion of the site (only available to dealers or owners) I'll PM a copy to you.

Based on that, your downline expanders will be pulling off the auxiliary supply, not the Elk's main supply. You can continue to add more of these power supplies to handle anything you attach to the M1. Of course you want to make sure no single power branch exceeds what its's rated for.

I was referring to the power supply does nothing to extend or boost the 485 bus, which is DATA A and DATA B, which is limited to the 4000'. It only provides additional aux power output to connected loads so they can be shed off the panel, and the supply itself supervised by the panel for trouble conditions via the 485 bus. The power connection is different than the 485 connection, since the 212 only uses 3 wires to connect to the panel, and other boards downstream do the same, with the exception that their power is drawn off the supply's output on the bottom of the 212.

Wuench- The M1's bus really doesn't provide that much power when you factor in any expansion boards and their draw, so power supplies are quite common and necessary when integrating a decent sized M1 that has expansion boards installed or even a moderate alarm panel by any other manufacturer. The methods he's considering, or at least I'm envisioning using the XOVR and M1RB is no different than what I believe you're proposing using other hardware.It would not be prudent to design the system without considering the current draw of all the peripherals in a full/max draw state, otherwise that is engineering in a failure out of the gate. 30 relays or outputs really isn't unheard of or excessive, depending on what the M1 is being used to control or integrate with.

Here's the facts as I know them:
The LV lights are driven off a few 120V transformers, which he wants to break up into zones/areas and control individually. Switching the 120V here would only do a generic on/off per transformer and not control the loads connected to the transformer, which does not match the "zone/area" that the OP would like to control.
There are sprinkler valves/irrigation controls being desired, which requires a relay per valve/zone
Any other need that may arise to use a relay, such as OHD opener, alarm power reset, LED for arm status, what have you.
 
I was referring to the power supply does nothing to extend or boost the 485 bus, which is DATA A and DATA B, which is limited to the 4000'. It only provides additional aux power output to connected loads so they can be shed off the panel, and the supply itself supervised by the panel for trouble conditions via the 485 bus.
Well - glad that's cleared up - because when I read your answers they seem very clear to me that you're saying this won't increase the ability for the P212 to boost the power on the data bus. Databus length has never come up as a concern on this thread or the one it stemmed from; the problem he was trying to solve was keeping the relays from drawing too much current from the databus and overloading the system... which this solves.

wuench: earlier ideas were tossed around regarding cascading relays and using separate power supplies - this is an extension of an earlier thread by the OP. Ultimately he will be cascading relays to zone out the lighting areas and provide protection, since the OP will be mounting the cascaded relays outdoors. Honestly I think Kid is doing it one of the easier ways given the volume... separating it out on the 120V side would be very costly given the number of separate transformers and appliance modules it would require for the desired effect. Using relays in this manner will only cost a fraction, even if he does take into account power distribution modules and aux. power supplies - not to mention it should provide for a pretty cool effect. The whole approach seems pretty well thought out to me.
 
I truly appreciate all the help, comments and ideas. This has been very informative for someone who knew absolutely nothing about the M1 a couple weeks ago.

I have ordered all my equipment (for this phase) and should have it within a week or so. I already received the M1 and the PS212. I may end up with more than 1 PS212, but I will wait and see on that. For now, I need to spend a couple days under and over the house running wires.

I will post a schematic of the system soon assuming I have the ability on the forum. Us newbies are restricted a bit.

One thing I was able to do was find an easy way to control the 120V power to the low voltage lighting transformers. I had mentioned I wanted to try to control the 120V side in addition to the low voltage side so that the transformer isnt powered when I am not using the lights. My transformers have a light sensor loop (optionla light sensor) which is a plug with the two conductors jumped with a couple inches of wire. I contacted the manufacturer and the product engineer told me they put the loop of wire there to allow for a clamp on meter to check the transformer. I asked if he could provide me the make and model of the plug which he did. I ordered a few plugs and pins. I am going to wire another relay into that loop to control the 120V power on the transformer in additon to the multiple zones on the low voltage side.



Thanks again for all the help.
 
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