Woodward 505XT, Installation And Operation Manual, Page: 48 / 242

Manual 35018V1 505XT Digital Control System for Steam Turbines
Woodward 46
Troubleshooting Fault Codes
The CPU board runs diagnostics that display troubleshooting messages through the debug Service Port
and AppManager. Additional information on diagnostics tests, subsequent LED flash codes, and serial
port messages is contained in the VxWorks manual.
Table 2-13. CPU Fault LED Flash Codes
Failure Flash Code
CPU not operational, IOLOCK state Solid Red
RAM Test Failure 2, 1
FPGA Test Failure 2, 9
Watchdog not enabled 2, 10
RAM drive error 2, 11
Flash drive error 2, 12
Troubleshooting & Commissioning checks
Power checks

Verify proper polarity on power connections

Verify power source and wire size is sufficient for all loads

Verify input power voltage is correct (i.e.: low voltage unit is 18 V to 36 Vdc)

Verify PS(+) and PS(–) impedance to EARTH is > 10 M Ω
RS-232 wiring checks

Verify the RS-232 wiring uses a high quality shielded communication cable. For example, Woodward
2008-1512 (Belden YR58684) or equivalent low capacitance, shielded communications wire.

Verify the RS-232 wiring uses the signal common (COM1_GND)

Verify RS-232 network length is within specifications (typically < 50 feet)

Verify Signal wires (TX+,RX-) are not shorted to each other

Verify Signal wires (TX+,RX-) are not shorted to COM1_GND

Verify Signal wires (TX+,RX-) are not shorted to COM1_SHLD

Verify Signal wires (TX+,RX-) are not connected to PS(+), PS(–), EARTH

Verify COM1_GND is not connected to PS(+), PS(–), EARTH

Verify the overall cable shield is terminated to EARTH at only (1) location.
RS-485 wiring checks

Verify the RS-485 wiring uses a high quality shielded communication cable. For example, Woodward
2008-1512 (Belden YR58684) or equivalent low capacitance, shielded communications wire.

Verify RS-485 network length is within spec for the baud-rate (typically < 4000 feet)

Verify the network is terminated properly at both ends with approx. 90–120 Ώ

Verify the RS-485 wiring uses the signal common (COM1_GND)

Verify Signal wires (RS-485+, RS-485–) are not shorted to each other

Verify Signal wires (RS-485+, RS-485–) are not shorted to COM1_GND

Verify Signal wires (RS-485+, RS-485–) are not shorted to COM1_SHLD

Verify Signal wires (RS-485+, RS-485–) are not connected to PS(+), PS(–), EARTH

Verify COM1_GND is not connected to PS(+), PS(–), EARTH

Verify the overall cable shield is terminated to EARTH at only (1) location.