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Yellow comm LED
The yellow comm LED blinks at the
rate the controller receives
communication.
Table 7 - Yellow Comm LED activity
Yellow LED activity
LED off continuously
LED blinks or flickers
LED on continuously
Manual output test
The test sequence verifies output
and end device operation. The
manual output test can be conducted
to verify output wiring and actuator
operation without using a service
tool.
Many service calls are initiated due
to diagnostics, so the test sequence
attempts to clear diagnostics and
restore normal unit operation prior
to testing the outputs. If the
diagnostics remain after an attempt
to clear diagnostics, the status LED
lights in a two-blink pattern,
indicating the diagnostic condition is
still present.
Translating multiple diagnostics
The controller senses and records
each diagnostic independently of
other diagnostics. It is possible to
have multiple diagnostics present
simultaneously. The diagnostics are
reported in the order they occur.
Resetting diagnostics
There are many ways to reset
diagnostics:
• Automatically by the controller.
• By initiating a manual output test at
the controller.
• By cycling power to the controller.
• By using a building automation
system.
• By using the Rover service tool.
• By using any other communicating
device able to access the
controller's diagnostic reset input.
• By cycling the fan switch from off to
any speed setting.
30
Troubleshooting
The yellow LED does not blink when
the controller is transmitting
communication data. Table 7
describes the different patterns.
Description
The controller is not detecting any communication.
(Normal for stand-alone applications.)
The controller detects communication.
(Normal for communicating applications,
including data sharing.)
Abnormal condition or extremely high traffic on the link.
Automatically:The Tracer ZN.520
zone controller includes an
automatic diagnostic reset function.
This function attempts to
automatically recover a unit when
the Low Coil Temperature Detection
diagnostic occurs. After the
controller detects the Low Coil
Temperature Detection diagnostic,
the unit waits 30 minutes before
invoking the automatic diagnostic
reset function. The automatic
diagnostic reset function clears the
Low Coil Temperature Detection
diagnostic and attempts to restore
the controller to normal operation.
The controller resumes normal
operation until another diagnostic
occurs. If a Low Coil Temperature
Detection diagnostic recurs within 24
hours after an automatic diagnostic
reset, you must manually reset the
diagnostic.
Manual output test:You can use the
Test button on the controller either
during installation to verify proper
end device operation or during
troubleshooting. When you press the
Test button, the controller exercises
all outputs in a predefined sequence.
The first and last steps of the
sequence reset the diagnostics.
Cycling power: When someone turns
off the controller's 24 VAC power,
then re-applies power, the unit cycles
through a power-up sequence. By
default, the controller attempts to
reset all diagnostics at power-up.
Diagnostics present at power-up and
those that occur after power-up are
handled according to the defined
diagnostics sequences.
Building automation system: Some
building automation systems can
reset diagnostics in the Tracer ZN.520
zone controller.
Rover service tool:The Rover service
tool can reset diagnostics in the
Tracer ZN.520 zone controller.
Diagnostic reset: Any device that can
communicate the network variable
nviRequest (enumeration
"clear_alarm") can reset diagnostics
in the Tracer ZN.520 zone controller.
The controller also attempts to reset
diagnostics whenever power is
cycled.
Cycling the fan switch: If the user
cycles the fan speed switch from off
to any speed, the controller resets all
diagnostics. Diagnostics may recur
immediately if the problem still
exists.
CNT-SVX13B-E4
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