Elk M1 Ethernet Interface power source

Hi,
New to posting here, but have been lurking a while designing a M1 Gold system. I'm in the process of doing the install and ran into a question that I can't find the answer to.

I want to power the ethernet interface from the control terminals labeled +vaux. It says it's rated for 1.25A and the spec on the ethernet interface is .3A. Any reasons not to do this?

My logic is that this will provide the ethernet interface with battery power and eliminate another object in the install can.

I'm working on an install during a total house remodel. Will eventually cover house and detached garage. Purchased all my parts through Automated Outlet here in Houston. They have been very helpful, but they are closed today.

Yes, you can power the ethernet interface from the VAUX supply, as long as it doesn't overload the power supply's 1A capacity.  Although the M1 supply is protected by 1.25A PTCs, that is an overload value.  The rated output is just 1.0A.  In general, you should allow some margin on this, so it is good practice to keep the total load below 0.8A.  This includes everything you power through the M1:  the M1 itself, keypads, zone expanders, sensors such as PIRs, glassbreaks, etc.
 
Elk has a current draw spreadsheet that will help you calculate your loads.
 
http://www.elkproducts.com/Owner_support_tools.html
 
One thing to consider... if your power goes out, do all your other network devices (switches, routers, modems) have backup power to keep them running?  If not, running the M1XEP off of a battery backed supply won't do much good.

Thank you... this is exactly the information I was looking for.  I'm building a fairly complex system.
 
I'm anticipating a few keyboards, a couple of input expanders, a ethernet interface, probably a wireless interface at some point and 35 to 40 sensors.  Because the whole house is open and we are replacing all the doors and windows it provides an easy opportunity to install a sensor on every door and window.  In addition, I am putting a sensor on each bedroom door and my office door.  I don't have a need for it right now, but if I rent out a bedroom it might be nice to give the renter the peace of mind of being able to "secure" their room.  
 
I'm planning on the control and an input expander in the house with a input expander in the garage to handle the sensors out there.  The garage is an "add-on" that I'll get to later when I re-wire and re-vamp the garage.  I am installing a retrofit hub from the get go.  The guys at AO (automated outlet) recommended going with a 4 wire bus and the retrofit hub instead of the modular hub.  They said it keeps the wiring simpler.  The goal of installing a hub is to provide easy system flexibility for future changes.  I'm anticipating the keypads being on one leg of the bus and the network and expansion module on another leg, and the garage on a separate leg, leaving one leg free.  
 
It is saying an auxillary power supply will be needed.  What is the best practice on where this should be located?
 
You make a good point about the UPS requirements.  My day job is as an IT Manager, so I keep all my network equipment on UPS units with ample capacity to run them during an outage.
 
My "hobby" job is designing embedded devices based on the Atmel Atmega 328 series of chipsets that use the Arduino environment for programming.    
 
My last alarm system was a DSC Power 832, but that's been a while and the Elk M1 Gold is a more flexible, more powerful, and more complicated system.

Depending on what loads you want to power with the auxiliary supply, it may make sense to locate it near them, but that's not always practical or possible.
 
For example, if you locate an input expander at a remote location from the M1, then you could locate the aux supply there as well.  But if the input expander is in an unheated garage, that may make it a poor place for the aux supply if it gets too cold (especially below freezing).
 
Wherever you decide to locate the supply, just make sure you use wire of an adequate gauge to carry the power to the remote devices you connect to it.  Devices like keypads and input expanders that connect to the M1's data bus can cause problems if they see too much of a voltage drop over a long cable.
 
Elk offers a couple of power supply options, but Altronix also makes good power supplies that are worth looking at.  You can often get a good deal on them on eBay.

For the garage it will make sense to have a remote power supply.  The garage will be insulated, heated, and cooled.  The HVAC in the garage will probably only be used to prevent freezing and make it comfortable when I'm working out there.... 
 
What is the normal way to use an Altronix power supply with an Elk?  It seems like the control is a bit weak in terms of only being able to pass through 1.25A when it's pretty easy to consume that with a complex system.

The M1 has enough power for a modest configuration, but once you start expanding it with add-ons, you need aux power supplies.
 
There are a lot of Altronix power supplies to choose from.  Depending on how much of a load you need to power, something like an AL300ULPD4 or AL400ULPD4/8 would probably be fine.  Also, the eFlow3N4 and eFlow4N8.  All of these have trouble contact outputs that indicate AC power loss and low battery conditions, and can be connected back to the M1 so that it can report a problem.
 
Normal practice with an aux power supply is to connect the DC negative output of the power supply back to the DC negative terminal on the M1. This provides a common power reference for the entire system (do NOT connect the DC positives together!).  So if you are placing the aux power supply in the garage, make sure you run an extra wire back to the house for this purpose.
 
If you place an input expander in the garage, I would not connect the power supply trouble outputs to this expander's inputs, since it is powered by that same supply.  Rather, run a cable back to the M1 and connect the trouble contacts up there.

good suggestion on monitoring the remote power supply.  I saw the schematic and notes about negative and positive... but I appreciate you mentioning it anyhow.
 
What I am thinking is:
- Stock wall wart directly to M1 Gold and it's included 8ah battery.  This will power the retrofit hub and first keypad and ethernet interface.
- Remote Power supply in garage with dedicated battery and home-run monitoring cable. This RPS is to power the input and output panels that will wind up in the garage.
- additional power supply, maybe a P624 with it's own 8ah battery.  This would be to power everything that attaches to the hub, which right now is looking like it will be 3 keypads, some motion sensors, smoke detectors, and a port expander.  Might be better to do another remote power supply here so it could be monitored.  Oh and of course home automation bridges.  
 
I'm sure I'll find other toys to attach down the road.  

Might make more sense to make the secondary power supply a P1215 with an 8 or 12ah battery depending on what the load calculations tell me.

The P1215 is ok if you just need a small power supply.  As with the main M1 power supply, be conservative and don't load it up to more than 80% of it's rated capacity so you have some head room.
 
When you choose batteries for the aux supplies, make sure that the amp-hour rating of the battery is large enough so that it will outlast the battery on the M1.
 
For example, suppose you have an 8 Ah battery on the M1, and the load on the M1's power supply is 0.8A.  Dividing 8 by 0.8 suggests that the battery will last about 10 hours (in reality, a bit less than that).
 
If you have a P1215 with a load of 1.2A, you would need something larger than a 12 Ah battery (1.2A x 10 hours) to equal the run time of the M1's battery.  So best to go with something like a 14 or even 18Ah battery.   But if the load is smaller, say 0.6A, then an 8Ah battery would probably be fine.  If, at a later time you add more stuff and increase the load, you may need to also increase the battery capacity.
 
If your aux power batteries run out before the M1's battery, the M1 will be unhappy about the loss of the components they power, and will trigger an alarm.
 
Bottom line is that battery size selection deserves careful consideration.

I personally would most likely do the Elk P212S since it is specifically designed for this; it hooks into the databus to communicate any status or issues, and is already designed to power the downstream devices hooked up after it.  Seems simpler than having to run separate status sensors back to the main panel.

Depends on if there's going to be an expander available or not. The more and more I'm dealing with M1's and 212's, the more I find myself going to Altronix and then tying to a zone. Yes, it's nice to have a controllable output with a power supply, but the cost vs. a capable altronix is a point to consider.
 
System design is going to drive the 212 installs for me.
 
The one thing I can say is if you run an XEP off a supply (or even not), It's not a bad idea to run the DC power through a controllable relay. Can save a ton of headache in the long run.

Do you mean to to power cycle the xep via the relay?

Yeah - there were once Elk examples to monitor for ethernet trouble and reset the XEP; it can be handy on the occasion that you can't reach it.  I'm sure one could easily setup a watchdog as well using external monitoring to trigger an input on the M1 to reset as well.

Work2Play said:

Yeah - there were once Elk examples to monitor for ethernet trouble and reset the XEP; it can be handy on the occasion that you can't reach it.  I'm sure one could easily setup a watchdog as well using external monitoring to trigger an input on the M1 to reset as well.

Click to expand...

 
I don't know if you've read any of the other thread (Topic about automating a gate) where I've mentioned the ease of using a RPi, but it can do what you've mentioned very easily and for under $100 it could be used to do a lot of other things too.

I wound up using a 212 remote power supply.  I wanted it to be supervised and that was what Automated Outlet recommended.  It was very easy to install and configure.  So far I have not had any headaches with the 485 bus.  I'm being very careful though.  I like that it saves a zone because it's on the bus.  Took a few minutes to figure out how to configure the RP software, but once I got the hang of it I didn't have any issues.
 
I'll give some thought to the ethernet on a relay.  That's an interesting idea.