LN-Display Installation Instructions
7
Troubleshooting
Table 1 describes possible troubleshooting problems
and solutions.
Table 1: Troubleshooting
Problem
Cause
Solution
Device is powered but
does not turn on.
Fuse has blown
(Auto-reset fuse)
Disconnect the power, the inputs, and the output terminals. Wait a
few seconds to allow the auto-reset fuse to cool down. Check the
power supply and the input/output wiring. Reconnect the power.
Power supply polarity
Verify that consistent polarity is maintained between all controllers
and the transformer. Ensure the COM terminal of each controller is
connected to the same terminal on the secondary side of the
transformer (Figure 11).
Device cannot
communicate on the FTT
network.
Absent or incorrect
supply voltage
Check power supply voltage between 24 VAC/DC and COM pins to
ensure that it is between acceptable limits. Check for tripped fuse or
circuit breaker.
Overloaded power
transformer
Verify the transformer used is powerful enough to supply all
controlled devices.
Network not wired
properly
Verify the wire connections are correct.
Absent or incorrect
network termination
Check the terminations.
Device communicates
well on short network
but does not
communicate on large
network.
Network length
Check the total wire length to verify it does not exceed the
specifications.
Wire type
Check the wire type to verify it meets the specifications. Ensure you
are using unshielded wire.
Network wiring problem
Verify the wire connections are correct.
Absent or incorrect
network termination
Check the terminations. Incorrect or broken terminations make the
communication integrity dependent upon a device’s position on the
network.
Extra capacitance
Verify that no extra capacitance is connected to the network other
than the standard FTT circuit and a maximum of a 10 ft (3 m) stub (in
bus topology).
Number of devices on
network segment
exceeded
The number of devices on a channel should never exceed 64. Use a
router or a repeater in accordance to the specifications.
Network traffic
Query node statistics to check errors. Use a LON protocol analyzer to
check network traffic.
Status
Light Emitting Diode
(LED)
1
Off
The device is in normal operation
or
the device is not powered.
If the device is not powered and the LED is Off, press the Service Pin
to light up the LED display.
On
The device has no application. Reload the application file (.apb).
Slow Blink
1 second On,
1 second Off
The device is not configured. Commission the device.
Fast Blink
1 second On,
1 second Off
Watchdog time out. The application is corrupted.
Call your Johnson Controls representative to report the problem.
1.
The Status LED is located on the bottom right of the LCD display. It emits an orange light when the device is ON.