CCN COMMUNICATION PROBLEMS- PART III

[algoodrow]

Following are actual troulbeshooting events that we have experienced that caused
communication problems.

Lack of communication and loss of communication are almost always a wiring issue.
As painful as it is, the buss wire can be at times easier to replace than to troubleshoot.
Gen III, in particular, doesn't offer easy buss access. 3V, on the other hand offer access
at any actuator or Priemierlink in the system.
Service situation #I: During a weekly remote (via telink) check of a 3V VVT system, we found the following:

Two minutes into the session, all devices on the buss were non- responsive. The
lower task bar on the computer declared the connection to still be established with
the modem. The only way to actually reconnect to the devices on the buss was to
disconnect form the modem and then dial back in. Two minutes of communcation
led to another session of no response for devices. A tech was dispatched and this
is what he found. Three devices, apparently, were added to this buss after the main
system was installed. All three of these devices were tee''d into the buss. The end
result were communication collisions were happening.
The solution was to rewire those elements to be in the series on the buss.

Situation II:

Communication loss every evening at 8:15PM. The system is i-Vu CCN 106
points. The majority of the points are: individual split systems, some with
3V-VVT zoning. One of our office staff who regularly monitors our i-Vu projects,
was checking trends on this particular project. She reported that one of the secondary
busses would lose communication with the rest of the system from 8:15'PM until
7:30 AM. We dispatched a tech, who ran a buss check. He didn't find anything.
He remade connections and checked primary and secondary control voltages.
The situation continued. We decided to have a tech on-site to the check the
buss activity at 8:15 PM that night. He was tied into one of the Primierlinks
on the problem buss and almost exactly at 8:15 PM the buss lost commucation.
The solution was to put the repeater on that buss on it's own circuit. One of the
security people was turning off the circuit breaker for that circuit, which also
had lighting on it, during his 8:15 PM rounds.

Situation III:

We got a call from a company who had been chasing a communication issue
for months. They also had been losing actuator motors randomly. This part-
ticular system was upgraded from Gen III to 3V during the past year. The
original zone valves were in place and had been fitted up with comfort I.D.
actuators. Our tech found the following:
The original system had been wired with standard 18 AWG single strand
cable. The new buss wire was 18 AWG stranded shielded. Two problem
areas were found. The original cabling, which was somewhere around 18
years old, had in some case been pulled tight to attach to the new hardware.
In one instance, the individual conductors wre bare, due to the wrie pulling.
The other situation involved the new buss wire. When installing a busswire
the drainwire (bare aluminum wire) needs to be continuous and needs to be
grounded at one end. At every device, the buss is attached to the drain wire
must be wired nutted together. The ground for the drain wire must be a
proper building ground.
Solution: Replace all the single strand cabling with 18 AWG stranded. Connect
the buss drain wire and ground it. We also learned this the hard way. Now all
our cabling is 18 AWG stranded sheilded and plenum rated. It costs a little more
but put up against the labor costs to rewire there is no comparison.