Troubleshooting Faults on SLC Controller

The major error fault code, indicates the probable causes of faults, and recommends corrective action. The following section describes the different ways to automatically clear a fault using your programming software.

AutomaticalIy Clearing Faults: SLC Processors

• Set the Fault Override at Power up Bit S:1/8 in the status file to clear the fault when power is cycled, assuming the user program is not corrupt.
  
  
• Set one of the auto load bits S:1/10, S:1/11, or S:1/12 in the status file of the program in an EEPROM to automatically transfer a new non-faulted program from the memory module to RAM when power is cycled.
• Refer to Status Bits for more information on bits S:1/13, S:1/8, S:1/10, S:1/11, S:1/12, S:5/0-7, and S:36/0-7. You can declare your own application specific major fault by writing your own unique value to S:6 and then setting hit S:1/I3.

Manually Clearing Faults: SLC Processors

• Manually clear the major fault bit S:1/13, and the minor and major error bits S:5/0-7 in the status file, using a programming device or a Data Table Access Module. Place the processor in the REM Program mode. Correct the condition causing the fault, then return the processor to either REM Run or any of the REM Test modes.
  
  
• SLC 5/03 and SLC 5/04 specific - Toggle the key switch from RUN to Progrram and then back to RUN.
  
  
• SLC 5/03 and SLC 5/04 specific - Clearing these bits with the keys witch in the RUN position causes the processor to immediately enter the Run mode.
  
  
• If you are online with a SLC 5/03 or SLC 5/04 processor with the keys witch position is in RUN and you press the clear major fault function key, you are warned that the processor will enter the Run mode once you clear the fault

Using the Fault Routine

When designating a subroutine file, the occurrence of recoverable or non-recoverable user faults causes the designated subroutine to be executed for one scan. If the fault is recoverable, the subroutine can be used to correct the problem and clear the fault bit S:1/13. The processor then continues in the run mode. If the fault is non-recoverable, the subroutine can send a message via the Message instruction to another DH-485 node with error code information and/or does an orderly shutdown of the process. The subroutine does not execute for non-user faults.