84
APPENDIX C — INPUT/OUTPUT BOARD (IOB) STATUS INDICATORS
All control boards have LED indicators that show control
board and communication status.
A red LED on each control module operates in the following
manner:
• Power not present or power supply failure: LED is off
• Power present but microprocessor in Reset: LED is off
• Microprocessor operational but not communicating: LED
flashes 3 seconds on, 3 seconds off
• Microprocessor operational and communicating with con-
trol system: LED flashes at 0.5 Hz rate (1 second on, 1 sec-
ond off) in sync (±100 ms) with all other new control mod-
ules on the same communication bus
• Microprocessor in boot mode: LED flashes at 0.2 seconds
on, 0.2 seconds off
Each independent communication port has a green status LED.
The green LED is on when data is being transmitted by the
board.
All RS485 ports have a green LED.
