Powering remote expansion boards, etc.

Just want to make sure I'm doing this right...
 
I have three remote cans, each containing a DBH and one or more expansion boards. Currently, all the remote expansion boards are getting their power from the M1G via the DBH's (using cat5e cables for the connections). Two of the cans are within a few feet of where I'm putting an Altronix 12VDC 10A PS. The other can is next to where I'm relocating a Elk P412 PS.
 
First... to create a common negative, I can run a wire from 12VDC(-) terminal on each PS to the 12VDC(-) terminal on the remote can's DBH. So the Altronix PS will have a wire running from its negative to each of the two DBH negatives in the nearby cans, and the P412 PS will have a wire running from its negative to the DBH negative in its nearby can.
 
Second... On each expansion board, I can clip the two 12VDC power wires coming from the DBH and run power supply wires from the expansion board to the PS.
 
Third... Even though I have room on a zone expander near the Altronix (that the Altronix will be powering), is it best to run the Altronix supervision contacts to zones in my "main can" (that contains the M1G). My concern is that if the Altronix fails hard, the zone expander powered by it will lose its connection, so the M1G detection will be less specific (lost expanders(s) communication instead of both Altronix failure and lost expander(s) communication). The Altronix will be powering an Uplink 2500 and some other pretty important stuff, so failure notification is important. The P412 will be powering stuff that isn't as important, and I have other ways to detect failures. Alternatively, would it be better to continue to power one remote zone expander via the M1G/DBH and connect the Altronix supervision relays to zones on that expander?
 
Does the above sound correct, or is there a better way?
 
Thanks,
Ira

I would get rid of the DBH's....I fail to see where they really save any work in 99% of the installs out there just for this reason.
 
Pay attention to the commons with multiple power supplies and separating them. In doing this, any potential difference...is voltage.
 
With a larger M1, you need to plan a standby battery for the main panel to be large enough, but the ones for the aux supplies need to have more capacity than the main panel if they drive anything on the bus.
 
The M1's bus doesn't like anything less than 12V, so you need to make sure the supplies have a 0V loss when running on battery only (many Altronix lose 1-1.5 V in the conversion unless you specifically use a 0V cutover supply). Once the bus starts dropping towards 12V, you'll get tons of reboot/restart and fails on it.....and every zone going into alarm/trouble/restoring....and creating a huge mess, log and especially if you monitor it.

The Uplink needs about 2A of clean headroom, so you need to plan that on the host supply.
 
It's doable, but you really need to pay attention to what is powered by what and the standby and backup on the system...and the supplies need to be rated for the full alarm load, not just standby.

DELInstallations said:

any potential difference...is voltage.

Click to expand...

 
:blink:

A bad late evening point, but when separating supplies by distance and attempting to make them all common, it's very easy for them to not have a true common reference to the host panel and each other.....which means now there's an inbalance occurs and strange things start happening (errors, reboots, etc.)

DEL...
 
The voltage on my Elk P412 PS drops from 14VDC to 10.8VDC when I shut off AC power. The install guide for the eFlow102N16 says the output voltage range is 10.03 to 13.2VDC so I'm guessing it does something similar. But, even if there is no immediate cutover voltage loss, won't the voltage eventually drop below 12VDC when on battery power (for a long enough time), thus causing the problems you mention?
 
Do the bus problems only surface if the external PS is powering an expansion board, or do they potentially occur whenever an external PS connected to a common ground (even if the PS isn't powering any expansion boards) drops below 12VDC?
 
I'm trying to get my remote M1XOVR's off of the M1G bus power because they are so power hungry. If the Altronix PS's may cause problems, and the Elk P412 may cause a similar problem, what is the best solution? Since you can add 12 M1XOVR's, there's got to be a reliable way to power them. Is there any PS available that won't potentially cause problems when on batter power?
 
You said "Pay attention to the commons with multiple power supplies and separating them." I don't understand what you meant by this.

Ira said:

DEL...
 
The voltage on my Elk P412 PS drops from 14VDC to 10.8VDC when I shut off AC power. The install guide for the eFlow102N16 says the output voltage range is 10.03 to 13.2VDC so I'm guessing it does something similar. But, even if there is no immediate cutover voltage loss, won't the voltage eventually drop below 12VDC when on battery power (for a long enough time), thus causing the problems you mention?
 
Do the bus problems only surface if the external PS is powering an expansion board, or do they potentially occur whenever an external PS connected to a common ground (even if the PS isn't powering any expansion boards) drops below 12VDC?
 
I'm trying to get my remote M1XOVR's off of the M1G bus power because they are so power hungry. If the Altronix PS's may cause problems, and the Elk P412 may cause a similar problem, what is the best solution? Since you can add 12 M1XOVR's, there's got to be a reliable way to power them. Is there any PS available that won't potentially cause problems when on batter power?
 
You said "Pay attention to the commons with multiple power supplies and separating them." I don't understand what you meant by this.

Click to expand...

 
 
The M1 data bus is a RS-485 interface and, as such, it uses a differential balanced pair of wires to transmit data.  Exactly the same principle as ethernet uses.
 
A differential pair is fairly immune to noise and power supply voltage differences between the two ends.  As long as each power supply is adequate to power the receiver and transmitter circuits for the bus, the data bus should operate just fine.  A few tenths of a volt difference or even a couple of volts should not make a difference. 

Re: "Pay attention to the commons with multiple power supplies and separating them."
 
If you look at the bottom of page 12 of the install manual, you'll see that the negatives (blacks) are connected, and the positives (reds) are separated.  
 
Connecting the positives would be bad.  Very bad.

The bus isn't the issue with the M1, the issue is what happens to the connected devices when the voltage powering them sags....and in the case of the M1, the bus devices don't like running on less than 12VDC. Straight from Elk engineers themselves
 
I had a larger install where I had to troubleshoot this exact issue....outbuilding and bus with separate power supply that crashed on a power fail during the winter. The batteries sagged and there was a volt loss on the altronix supply....so 12.1 on the battery was 11.1 on the output.....lots of rebooting, comm loss, and the like.