Internal Error

What does 8705 mean?

An unspecified internal error has occurred within the Safety PLC, indicating a fundamental hardware or firmware issue that prevents reliable operation. This type of error demands immediate attention as it directly impacts the PLC's ability to maintain safety functions and could lead to hazardous situations if left unaddressed.

• Memory access violation within the safety PLC's operating system (firmware kernel) or application space.
• Hardware watchdog timer expiration due to CPU overload, internal bus contention, or a deadlock condition.
• Corruption of the safety program or hardware configuration data stored in the safety PLC's non-volatile memory.
• Internal component failure (e.g., a specialized safety ASIC or communication controller) on the safety PLC module's circuit board.
• Electromagnetic interference (EMI) causing transient data corruption within the PLC's internal registers or communication buffers.

Click steps to track your progress.

1. 1

   Record the specific diagnostic data available on the safety PLC's display or through the engineering software, including any sub-error codes and timestamps.

2. 2

   Verify the stability of the 24VDC power supply to the safety PLC module using a multimeter, checking for ripples or drops below 21.6VDC during operation.

3. 3

   Perform a firmware consistency check or integrity test if such a function is available within the safety PLC's engineering environment.

4. 4

   Download the original, verified safety program and hardware configuration to the PLC, ensuring no discrepancies exist between the project and the device.

5. 5

   Check all wiring connections to the safety PLC for proper shielding and grounding, especially for I/O and communication cables, to mitigate potential EMI.

6. 6

   If the error persists after power cycling and re-downloading, replace the safety PLC module with a new unit of the exact same part number and firmware revision.