Initialization Incomplete: Cannot Retrieve Nodes from ISY

[jeffreycowart]

Was freaking out last night as I typed up the situation below.  Luckily, I discovered the issue and all is good now, but thought I would still post for anyone else who has my lucky timing...  

Here was the situation:

ISY994 All Z-wave, no Insteon.  UI and Firmware on 5.3.4

My ISY994 has been running just fine, until today when I added a Zooz ZAC38 Range Extender.  I did my normal process of exclude twice, then included the device using the UD mobile app.  I always have it show progress.  It added a bunch of nodes, but it seemed like it might have stopped/stalled before finishing.  Seems like I usually read something in the progress that tells me it's finished.  I waited approx 1 minute and there was no movement, so I clicked the finish button.  It asks if I wanted to synchronize, I said yes and it went through it's process (I thought).  It then asked me if I wanted to delete 1,5xx old cached values, which I thought was odd, since it is usually a very low number.  I said no, then went to the admin console.  I get the error: "Initialization Incomplete: Cannot retrieve nodes from the ISY.  Would you like to close the Admin Console."  First times I said yes.  Then tried clicking no, it goes to admin console, but only ISY is at the top no z-wave nodes.  Elk is showing status, programs are there, but they are all "unrecognized nodes"

I have:
Rebooted ISY via UD mobile
Unplugged ISY for 60 seconds
Removed SD card and cleaned contacts
Cleared Java Cache and got a new start.JNLP
Excluded new ZAC38 device via UD Mobile
Z-Wave Synchronize nodes via the Z-wave drop down.  It tried and went through the process twice (status bar showing progress).  On second attempt, the status bar just went away.  (Below I noticed using the event viewer that one device was flooding the viewer during the sync).

Was about to factory reset the Z-wave dongle, thank goodness I didn't.

Z-wave continues to work and I can remote control devices via UD Mobile (i.e. turn lights on/off).  If I try to synchronize UD mobile it freezes at Z-wave instance 1...  After a while it continues with lots of errors: ISY header no response, etc.  Since the sync fails, the z-wave devices are still visible and can be used.

Through the admin console I was able to open the event viewer.  Level 1 nothing special going on.  Level 3 one device is providing an "Binary switch report" every second.  ISY admin console didn't show as "Busy" in the lower left corner, but it was a constant request.  This is a simple On/Off Homeseer HS-WS100 device.  That has been in place for approx 7 years.  Once I figured out which switch it was, I went and took a look.  It had the flashing LED indicator strobing at 1 hz.  The switch had gone bad.  I removed power to that switch and all was working as normal again!  It was basically causing a DOS attack on my system, but switch went bad right as I was adding the Zooz range extender, so I thought that was the culprit.  Or the switch was already flooding the network and the add device failed due to network traffic.

I have had these Homeseer (same as Jasco/Dragontech) go bad before, but they have never caused a DOS.  They just don't work locally or remotely.

FYI, these switches can be fixed by replacing a small capacitor on the start circuit.  I replaced the capacitor and the switch is back in place working fine now!