Troubleshooting field controllers
Observe the Status LEDs on the front of the equipment controller. The following table provides LED status
indicator information for troubleshooting the controller.
Table 6: Status LEDs and description of LED states
LED label
LED color
Normal LED state Description of LED states
POWER
Green
On Steady
Off Steady = No Supply Power. Check the Output wiring for short circuits and cycle
power to controller.
On Steady = Power Connected
FAULT
Red
Off Steady
2 blinks followed by long pause = Controller powered on in default state. For
more information about this default state, see
Input/Output Wiring Validation
.
Off Steady = No Faults
On Steady = Device Fault; no application loaded; Main Code download required, if
controller is in Boot mode.
Blink - 2 Hz = Download or Startup in progress, not ready for normal operation
Rapid blink = SA Bus communications issue
SA BUS
Green
Blink - 2 Hz
Blink - 2 Hz = Data Transmission (normal communication)
Off Steady = No Data Transmission (N/A - auto baud not supported)
On Steady = Communication lost, waiting to join communication ring
FC BUS
Green
Blink - 2 Hz
Blink - 2 Hz = Data Transmission (normal communication)
Off Steady = No Data Transmission (auto baud in progress)
On Steady = Communication lost, waiting to join communication ring
EOL
Amber
Off (Except on
terminating
devices)
On Steady = EOL switch in ON position
Off Steady = EOL switch in Off position
Repair information
If an equipment controller fails to operate within its specifications, replace the controller. For a replacement
controller, contact your Johnson Controls representative.
ATC1510 Advanced Terminal Unit Controller Installation Guide
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