Combining "Data Bus Hub" and "Data Bus Hub Retrofit"

[apu]

Does this configuration make sense? A short run from the control panel to a Data Bus Hub Retrofit and then connecting three Data Bus Hubs to the DBHR -- one nearby, the others are about 150 ft. away, connected back to the control panel via four conductor cables. The control is terminated as is each of the branches on the DBHR, and the terminating resistor is in the last unused port of each DBH.

Just making sure I'm not missing anything obvious here while I check the wiring on the other components. I have one output expander that disappears every once in a while and one keypad that is never seen during bus enrollment though it did mimic the display of keypad 1 before I changed its address so I'm fairly confident it is on the bus.

 

[gatchel]

I would go from the DBHR to the left DBH to the middle DBH and on to the right DBH and terminate there.

The DBHR manual states "The M1DBHR CANNOT be used as an extender or remote repeater."

I am not sure if that would apply to your diagram.

With RS485 there are a few rules that I like to use, twisted Pair cabling, terminate at the ends of the daisy chain, simpler is better, 4000' maximum.

 

[WayneW]

I have both, but they are both homerun to my M1. I recall that you could daisy-chain from one to the other, but not vice versa, So double check the spec sheets & info on the Elk site or search here. My instinct is that the DBH cannot go after a DBHR due to the latency of the DBHR, but verify that before believing me.

 

[WayneW]

I have one output expander that disappears every once in a while.

I have been troubleshooting an XOVR output expander that intermittently gives a trouble report (goes missing) and then instantly reappears. Elk has a fix for it in a beta version I am testing and results are good so far.

24,Fri 7/29/2011,09:33,,1161 = EXPANSION MODULE RESTORE,Output Exp. 2
25,Fri 7/29/2011,09:32,,1141 = EXPANSION MODULE TROUBLE,Output Exp. 2

 

[Digger]

I have been troubleshooting an XOVR output expander that intermittently gives a trouble report (goes missing) and then instantly reappears. Elk has a fix for it in a beta version I am testing and results are good so far.

24,Fri 7/29/2011,09:33,,1161 = EXPANSION MODULE RESTORE,Output Exp. 2
25,Fri 7/29/2011,09:32,,1141 = EXPANSION MODULE TROUBLE,Output Exp. 2

I have the same bug in a few panels. Drives people crazy in the middle of the night when the keypads start beeping etc. Hope they release the firmware soon.

 

[Del91574]

You'll need to modify how your wiring lands on the retro board from the field devices. You'll need to land 2 terminated branches on the first output then the 3rd on the next branch with a terminating resistor. The last 2 branches will have no connection, otherwise the panel won't see the branches properly.

I've had to cascade retro boards before and found out when I couldn't enroll devices.

 

[apu]

Thanks all for the various replies.

Wayne - Logistically, it will be very, very difficult to daisy chain from one DBH to another. As far as the output expanders, I'm leaning towards saying it is the bug you experienced as well; exact same symptoms once I removed the keypad (see below).

DEL - Tried that tonight. Had to go back to the original config as the system could not talk to anything in the middle branch for some reason. (First branch, which shared the same connector was fine, as was the third branch on its own connector.) Though, with the exception of my keypad problem (see below) the system seems happy with my config.

My own update - Since I was having problems with that one keypad, I disconnected it where it lands on one of the DBHs and moved the terminating resistor up. The frequency of data bus errors dropped dramatically.

Turned off the system and measured 65-70 Ohms on each of the branches as it should be. Plugged in the cable that goes to that keypad, and that goes up to 150 Ohms. Unplug the keypad from the other end but leave the cable connected to the DBH and the resistance stays in the 150 Ohm range. So we're obviously not shorted or open on the bus, but resistance goes up with that cable connected with or without the keypad actually plugged in to the cable.

What is that trying to tell me?

(I have another keypad location that I had not previously tried to bring online but it is having the same resistance increase with the cable connected on the DBH, even without the keypad connected. The other five keypads, and two supervised remote power supplies, plus all the input and output expanders, seem happy though.)