Multiple M1DBH wiring

IVB

Senior Member
Long time no post, the pandemic has me nuts as I'm a healthcare consultant. Hope all is well with all y'all.
 
I want to put up a 2nd M1DBH. I've totally misunderstood 19 million things in the last <n> units of time.
 
Question 1: Whadda youse guys think this line means?  "Two or or more M1DBH Hubs may be connected in a straight (single) daisy chain to increase the number of home runs"
 
It could mean:
1) Take the 4 wires from the main, run to the first M1DBH and also to the 2nd M1DBH. Bus is terminated on both M1DBH after the last device.
 
2) Take the last (9th) spot on the first M1DBH, connect that to the 2nd M1DBH.
 
Alas the problem is that i've had MASSIVE issues with my Elk ever since I had my Tesla solar installed. They redid the wiring at the main completely, I forgot to physically turn off the Elk, the new surge blew out tons of stuff. I replaced my my main, M1DBH, a few expansion boards. But still, I'm unable to get the last 3 ports on a brand new M1DBH working.
 
I realize my M1DBH issues are a different post but I was hoping to throw money at the problem and do option 1. 
 
Question 2:: What if I need a 3rd M1DBH (very likely)? If I homerun back to the main, I think I can terminate on all 3 M1DBH but it'll still be 1 contiguous line based on the answer above.
 
I use the retrofit version but the rules are the same:
 
The ELK-M1DBHR † Data Bus Hub Retrofit is intended for retrofit jobs where existing 4 conductor cables are the only wires available. It creates 4 managed RS-485 BRANCHES from the single M1 main RS-485 Bus.
 
Like the main M1 Bus, each branch can only have 2 home run cables (4 branches x 2 ea. = 8 home runs).
 
DO NOT connect more than two (2) M1DBHR Hubs to a single M1 Control.
 
DO NOT connect an M1DBHR on a branch of another M1DBHR!
 
The M1DBHR CANNOT be used as an extender or remote repeater.
 
DO NOT remote M1DBHR(s) away from the M1. Mount within main M1 Control. Terminate last (end line) device on each home run
 
So you will connect both hubs to the M1 with terminators and remove the terminatior on the M1 Control. The rerofit version does not allow for more than two on a single control so I am surprised about the "two or more" language and would try to confirm that somewhere.
 
In any case you would never put a hub on a branch of another hub... always off the M1 control.
 
upstatemike said:
I use the retrofit version but the rules are the same:
 
The ELK-M1DBHR † Data Bus Hub Retrofit is intended for retrofit jobs where existing 4 conductor cables are the only wires available. It creates 4 managed RS-485 BRANCHES from the single M1 main RS-485 Bus.
 
Like the main M1 Bus, each branch can only have 2 home run cables (4 branches x 2 ea. = 8 home runs).
 
DO NOT connect more than two (2) M1DBHR Hubs to a single M1 Control.
 
DO NOT connect an M1DBHR on a branch of another M1DBHR!
 
The M1DBHR CANNOT be used as an extender or remote repeater.
 
DO NOT remote M1DBHR(s) away from the M1. Mount within main M1 Control. Terminate last (end line) device on each home run
 
So you will connect both hubs to the M1 with terminators and remove the terminatior on the M1 Control. The rerofit version does not allow for more than two on a single control so I am surprised about the "two or more" language and would try to confirm that somewhere.
 
In any case you would never put a hub on a branch of another hub... always off the M1 control.
 
Alas the M1 is in a location where running new wires to it is now impossible. I created that 2ndary location because I figured I'd never need to get to it again. Didn't expect a situation where the secondary was blown and unrecoverable, but I wonder if that's what I need to triage now.
 
although, now I really do wonder what Elk means by "Two or or more M1DBH Hubs may be connected in a straight (single) daisy chain to increase the number of home runs"

That was lifted directly from the Elk manual.
 
IVB said:
although, now I really do wonder what Elk means by "Two or or more M1DBH Hubs may be connected in a straight (single) daisy chain to increase the number of home runs"

That was lifted directly from the Elk manual.
In my copy of the M1DBH directions, it says:
 
To connect more than 9 data bus runs, additional
M1DBH unit(s) may be connected together in a
daisy chain fashion. This connection requires a
"crossover" cable to be made using two (2) RJ45
connectors and a short length of CAT5 wire. See
diagram on back. Plug one end of the "crossover"
cable into connector J9 on the first M1DBH.
Plug the other end into connector J1 on the next
M1DBH.

 
If you have two M1DBHs, I think you should be able to connect each one back to the M1 with its own home run, then terminate both of the DBHs in the first unused jack position.  If you have a 3rd DBH to connect, you would have to daisy chain it off of J9 on one of the others.
 
The reason is that each DBH forms a branch of the M1 bus, and you can only have two branches. When you daisy chain them, the downstream DBH continues the branch from the DBH it is plugged into.
 
I'm not sure why a power surge would have damaged a DBH.  It is just wiring on a circuit board with no active components.
 
I disagree with @upstatemike that the DBH has the same connection rules as the DBHR.  They are not the same, as the DBHR contains active circuits that repeat the data bus signals.  This creates a totally different bus environment.
 
RAL said:
In my copy of the M1DBH directions, it says:
 
To connect more than 9 data bus runs, additional
M1DBH unit(s) may be connected together in a
daisy chain fashion. This connection requires a
"crossover" cable to be made using two (2) RJ45
connectors and a short length of CAT5 wire. See
diagram on back. Plug one end of the "crossover"
cable into connector J9 on the first M1DBH.
Plug the other end into connector J1 on the next
M1DBH.

 
If you have two M1DBHs, I think you should be able to connect each one back to the M1 with its own home run, then terminate both of the DBHs in the first unused jack position.  If you have a 3rd DBH to connect, you would have to daisy chain it off of J9 on one of the others.
 
The reason is that each DBH forms a branch of the M1 bus, and you can only have two branches. When you daisy chain them, the downstream DBH continues the branch from the DBH it is plugged into.
 
I'm not sure why a power surge would have damaged a DBH.  It is just wiring on a circuit board with no active components.
 
I disagree with @upstatemike that the DBH has the same connection rules as the DBHR.  They are not the same, as the DBHR contains active circuits that repeat the data bus signals.  This creates a totally different bus environment.
 
well crap. In that case I must fix my M1DBH issues as I can't even get to port 9, anything I plug into port 7 or 8 craps out.  And if I swap what's in port (ie 4) with port 7, what was on port 4/now 7 stops working, and what was on port 7/now 4 starts working.
 
I'll try that again in case I had anger issues and wasn't thinking clearly. It was a seriously pissed off time. I'm now down to 1 (of 3) keypads, 1 nonfunctioning M1XIN, and 1 nonfunctioning relay board. But most importantly key zones or relays just aren't happening.
 
Do you know the total length of the wires through the DBHs? Each home from the DBH to a data bus device (like a keypad or input/output expander) counts as 2x the length of the actual cable. The total length of the data bus needs to stay under 4000 feet. Any chance your cabling exceeds that?

If it was all working before, the only other thing I can think of is that maybe your Tesla system is generating a lot of RF noise that is being picked up on the data bus. The Tesla shouldn't be doing that, and the twisted pair wiring on the data bus should help reduce any interference, but I wouldn't say it's impossible.

I'm curious - what was it about the Tesla that caused a surge?
 
It might be as long as 150 feet total for all 3 DBH wires put together, but I doubt it :)  I separated them by floor: main floor, attic (immediately above M1), and basement (15 feet horizontally away). The 3rd DBH will be ~45 feet from the 2nd DBH but due to an odd run i'll have to zig zag.
 
I'm 99% sure the issue was electrical. My old wiring in the panel was so bad the Tesla electrician called me over to look at it. My house was built in 1911, put in the solar 2.5 years ago. I had never seen behind the main. It...was....horrifying.  The electrician said they needed a full day to untangle the mess. I can't remember exact numbers but I went from something like 14 circuits to 22 because they needed to tease so much stuff apart.
 
I wonder if, when the system came back online, there was so much more juice something got fried. Or perhaps finally closer to a clean sine, no idea, I switched to Comp Sci from Comp engineering cuz I disliked learning hardware details :)
 
RAL said:
In my copy of the M1DBH directions, it says:
 
To connect more than 9 data bus runs, additional
M1DBH unit(s) may be connected together in a
daisy chain fashion. This connection requires a
"crossover" cable to be made using two (2) RJ45
connectors and a short length of CAT5 wire. See
diagram on back. Plug one end of the "crossover"
cable into connector J9 on the first M1DBH.
Plug the other end into connector J1 on the next
M1DBH.

 
If you have two M1DBHs, I think you should be able to connect each one back to the M1 with its own home run, then terminate both of the DBHs in the first unused jack position.  If you have a 3rd DBH to connect, you would have to daisy chain it off of J9 on one of the others.
 
The reason is that each DBH forms a branch of the M1 bus, and you can only have two branches. When you daisy chain them, the downstream DBH continues the branch from the DBH it is plugged into.
 
I'm not sure why a power surge would have damaged a DBH.  It is just wiring on a circuit board with no active components.
 
I disagree with @upstatemike that the DBH has the same connection rules as the DBHR.  They are not the same, as the DBHR contains active circuits that repeat the data bus signals.  This creates a totally different bus environment.
I did not realize they were different apart from screws vs jacks so disregard anything I said as I only have info on DBHRs.
 
Wondering what the topology / system looks like here. You mention you may need maybe 3 hubs (implying > 18 devices on the bus) yet the wire distances are short. Just curious what is all connected to the data bus.


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not >18 devices, but rather a system designed for future extensibility without long runs.
 
Single story house, craftsman style, trivial access to the attic & crawlspace.
 
Main floor: Elk M1. But tiny area.
Basement: M1DBH #1: Most wiring goes here. Would love to have 8 devices on it but can't get them all to work
Attic: M1DBH #2: Relay, M1XIN for stuff in the front of the house.
 
Trying to put M1DBH #3 in a backyard office I'm building. Low Voltage has to be in a 6" deep trench, in conduit, so putting an M1DBH there means I can add whatever I want in the future without worrying about long runs. I know I want 2 window sensors, 1 door sensor, 1 motion detector, likely 2 different low voltage lights on relays. But inevitably I do more stuff. Having the M1DBH be in the office gives me that flexibility. 
 
Since you have multiple M1DBH's, does swapping one with another change anything with port 4 working, but not port 7 or 8?   That would allow you to narrow down whether this a problem with the DBH itself, or something with the wiring, connected devices or termination.
 
I just ordered another M1DBH, I think i'll try that first RAL. I haven't yet as it was more work than I had time for, esp given the craziness of work for the past 4 years.  Building a backyard office is pushing the agenda though.
 
Okay but if I understand you’re adding sensors. Those don’t go on the bus. An M1XIN (input expander) would go on the bus and you connect sensors to that. What am I missing?


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