Problems with Connecting the Elk Two Way Transceiver on a Retrofit Data Bus Hub

[urbanscribe]

Pulling my hair out a bit
 
Trying to wire up the ELK-M1XRFTW Two-Way Wireless Transceiver when using a ELK M1DBHR M1 Data Bus Hub For Retrofit
 
I've tried to connect M1XRFTW Transceiver a couple of different ways on the M1D Bus BHR but keep having usual termination or connection problems (connection lost, can't find the transceiver).  There is an existing ELK-M1KPB Keypad on Branch 1 terminated.  The main board is terminated as per usual.  The M1XRFTW is also terminated.  
 
Any insight on how to wire up the M1XRFTW transceiver with the M1DBHR bus and termination setup?
 
 
 
 
 
 

 

[Del91574]

One jumper on the board. Put 2 devices, terminated at the device, on the first branch on the DBHR, Branches 2,3,4 terminated. Once you terminate a branch on the DBHR, it won't pass the data downstream.
 
Guessing you're trying to put 1 device per branch? If so, it won't work.

 

[RAL]

Once you terminate a branch on the DBHR, it won't pass the data downstream.
 
Guessing you're trying to put 1 device per branch? If so, it won't work.

 
@DEL - I haven't had a chance to use a DBHR, but from reading the instructions, I read them as saying you can have just one device on a branch, as shown in the Branch 1 example.
 
My understanding is that each bus needs 2 terminators.  If there is only one device attached to a branch, then you need a terminator at the device and one on the DBHR jumper for that branch.  If you have 2 home runs on a branch, then you need one terminator at each end device, and none on the DBHR.  But the fact that the branch is terminated on the DBHR doesn't stop the other branches from working.
 
Did I miss something?

 

[Del91574]

Incorrect.
 
Once you put a termination on the branch, it kills data from moving downstream. You can't wire 4 devices to 4 branches, the correct way would be 2 branches, with each device terminated.

 

[drvnbysound]

@DEL - I haven't had a chance to use a DBHR, but from reading the instructions, I read them as saying you can have just one device on a branch, as shown in the Branch 1 example.
 
My understanding is that each bus needs 2 terminators.  If there is only one device attached to a branch, then you need a terminator at the device and one on the DBHR jumper for that branch.  If you have 2 home runs on a branch, then you need one terminator at each end device, and none on the DBHR.  But the fact that the branch is terminated on the DBHR doesn't stop the other branches from working.
 
Did I miss something?

 
Based on the document that's what I would have thought too... or possibly to have not put the jumper on branch 1, but to have done so on branch 2 to complete the bus. I haven't used a DBHR, only the standard DBH.

 

[RAL]

Based on the document that's what I would have thought too... or possibly to have not put the jumper on branch 1, but to have done so on branch 2 to complete the bus. I haven't used a DBHR, only the standard DBH.

 
The way I understand the DBHR instructions, each of the 4 branches, plus the connection back to the M1 are their own RS485 bus, and as such must have 2 terminators.  As long as that is the case, then it should be ok to have just 1 device on any bus, as long as there is a terminator on the corresponding DBHR branch jumper.
 
I believe what DEL is saying and that he speaks from experience and if you place a jumper on the DBHR, then the higher numbered branches become disabled.
 
If that's the case, it sure would be helpful if Elk would document that in the instructions, and not show an example that will not work.  It would have been better to place the single device in Example 1 on Branch 4.

 

[urbanscribe]

1. i was trying to put the keypad on branch 1 of the DBHR and the M1XRFTW on branch 2.
 
​2. accordingly i have now tried
- both Keypad and Transceiver connected to branch 1
- keypad terminated at keypad
- transceiver terminated at tranceiver
- JP3 terminated on board
- JP3,4 and 5 terminated on DBHR
 
so bus board to DBHR terminated at both ends
branch 1 terminated at both devices and not on DBHR
all other branches terminated on DBHR
 
i think that matches your setup DEL.  
 
no dice.  see images
comm lost to keypad
if i restore branch 1 as keypad and DBHR only the keypad comes back no problem.
 
what am i missing?
 
 
https://www.dropbox.com/s/42p75ya2zuo1dq8/IMG_8099.jpg?dl=0
 
https://www.dropbox.com/s/ne3fhxu20af45wv/IMG_8100.jpg?dl=0
 
https://www.dropbox.com/s/mrom3gq6ouo7xho/IMG_8101.jpg?dl=0
 
https://www.dropbox.com/s/9ui4sp8j7obdf4g/IMG_8102.jpg?dl=0
 
 

 

[urbanscribe]

per above conversation
btw i have tried the jp1 terminator on DBHR ON and OFF thinking maybe that stops the bus going to branch 1 but made no difference
 i agree the instructions are a little unclear what they mean by EXAMPLE 1,2 etc and give the impression you can do one device on branch 1 then two on branch 2 

 

[Del91574]

I use DBHR's quite often....we're on the "gold coast" where there's a lot of large and legacy systems. Some have enough cable to facilitate a daisy, some do not, and I've been against the 4K' limit of the panel before. Got really good on how and where to use them to leverage the 485 limitations.
 
A DBH is a passive device, no different than installing a RJ31X/38 and the shorting bar.
 
On the surface it makes sense, you should be able to land devices everywhere on the DBHR. In practice, what the DBHR does is cascade the data, so once you terminate the hub, it won't cascade the data to the next branch. It could go both ways....I see both sides of the fence from working on a lot of systems that use 485 data and hubs to manage supervision. I'd have to look at the board, but it's probably the location of the jumper and shunting the signal through the resistor before cascading downstream.

 

[RAL]

Try removing the DBHR and connect the one keypad and the TWXRF directly to the M1.  Leave the terminators on both, but remove jumper J3.
 
Does that work?  If you still get the lost comm message, then that suggests a poor connection to the keypad, or perhaps a problem with the keypad.

 

[Del91574]

JP3 on panel would be jumped
JP1 on DBHR would be jumped
JP2 on DBHR would be OFF
Each device would be jumped.
 
Then set the appropriate address on the devices and enroll.
 
If that doesn't work, you'll have to verify the units work individually at the panel, which would then point to a cabling issue or a bad device.

 

[urbanscribe]

RAL/DEL
 
i did just this to make sure
when both connected to the main board without DBHR connected, Keypad and Transceiver both connect just fine,
bus light lights up on the transceiver and communication to the Keypad no problems

 

[RAL]

RAL/DEL
 
i did just this to make sure
when both connected to the main board without DBHR connected, Keypad and Transceiver both connect just fine,
bus light lights up on the transceiver and communication to the Keypad no problems

 
Ok, that's good.  So now take another small step. 
 
Connect the DBHR up to the M1 again, with a jumper on JP3 on the M1 and JP1 on the DBHR.  Connect just the one keypad to branch 1, with a jumper on the keypad and a jumper on JP2, and no jumper on JP3, JP4, JP5.
 
Does that work?
 
Another test would be to connect the keypad to the M1, with a terminator jumper on the keypad.  Connect the DBHR to the M1 with a jumper on JP1.  No jumper on JP3 on the M1.  Then connect the XRFTW to branch 1 with a jumper on the XRFTW and a jumper on JP2 on the DBHR.  No jumpers on JP3, JP4, JP5.
 
One other question... how long is the cable that connects the DBHR to the M1?  The DBHR should be located close to the M1, with a short cable.

 

[urbanscribe]

1) ABOUT = Connect the DBHR up to the M1 again, with a jumper on JP3 on the M1 and JP1 on the DBHR.  Connect just the one keypad to branch 1, with a jumper on the keypad and a jumper on JP2, and no jumper on JP3, JP4, JP5.
 
that DID NOT WORK
funnily and bizarrely to me
it DOES work on the DBHR with
- jp3 on m1 = yes
- jp1 on BDHR = yes
- jp2  on BDHR = no
- jp3, jp4, and jp5 = yes
that makes NO SENSE to me since branch 1 does not seem dual terminated (no jp2 but keypad is terminated)
 
2= WILL TRY NEXT
 
3= very close, inside the box (i read about not having it far away)
cable run probably 6-8 inches

 

[RAL]

1) ABOUT = Connect the DBHR up to the M1 again, with a jumper on JP3 on the M1 and JP1 on the DBHR.  Connect just the one keypad to branch 1, with a jumper on the keypad and a jumper on JP2, and no jumper on JP3, JP4, JP5.
 
that DID NOT WORK
funnily and bizarrely to me
it DOES work on the DBHR with
- jp3 on m1 = yes
- jp1 on BDHR = yes
- jp2  on BDHR = no
- jp3, jp4, and jp5 = yes
that makes NO SENSE to me since branch 1 does not seem dual terminated (no jp2 but keypad is terminated)

 
I agree, what you are seeing doesn't make a whole lot of sense.
 
What wire are you using to connect the keypad?  Is it the old wiring from the old system?  Or are you just doing a bench test with some new 4 conductor cable to see how things should work?
 
If you are using the old wiring, the only thing I can think of right now is that there is something strange about it that is messing up the RS485 bus. 
 
With the keypad connected to the far end of the wire, and the other end disconnected from the M1 and DBHR, put an ohm meter across the two data wires (green and white) on the panel end of the cable and see how many ohms you read.  It should be about 120 ohms with the jumper in place on the keypad.
 
[Edit]: Well, after thinking about this some more, maybe it makes a little sense. As DEL posted in post #16 below, your jumper configuration is what he recommended previously for having 2 devices on branch 1.
 
With only the one keypad on branch 1, the branch does not have the proper termination of 2 terminator jumpers.  But RS-485 can be somewhat forgiving on termination, especially with shorter wire lengths and less-than-maximum data rates.  So it might be just a little bit of RS-485 "luck" that this configuration is working.  But it really should work with the second terminator on JP2 installed.  Not sure why it's not.  Which leads me back to being suspicious of the cable itself.