Internal Error

What does 8707 mean?

An unspecified internal error has been identified within the Safety PLC, signifying a potential hardware or firmware malfunction that affects the core functionality and reliability. This error can lead to unpredictable behavior and critically compromise the safety functions of the system. Immediate troubleshooting is required.

• Detection of an invalid instruction execution or an unhandled exception by the PLC's CPU, indicating a severe firmware issue.
• Safety-related diagnostic event detected by internal self-monitoring routines (e.g., a mismatch between redundant processing channels).
• Corruption in the internal data structures or registers essential for safety program execution and reliable operation.
• Failure of a specific internal ASIC or peripheral responsible for safety-critical functions (e.g., watchdog generation, internal time synchronization).
• Loss of synchronization between redundant safety processing channels within the PLC module (if a redundant architecture is implemented).

Click steps to track your progress.

1. 1

   Record all diagnostic information, including the specific sub-code, module identification, and timestamp, from the PLC's display or engineering software.

2. 2

   Check the integrity of the safety PLC's power supply rails at the module's terminals using a high-resolution multimeter, looking for voltage dips or noise below 21.6VDC.

3. 3

   Upload the current safety project from the PLC and compare it against the last known good version, checking for any inconsistencies or unauthorized changes.

4. 4

   Perform a memory test or diagnostic function on the PLC module if such capabilities are available through the manufacturer's engineering software.

5. 5

   Cycle the power to the safety PLC, waiting a minimum of 30 seconds before reapplying power, to ensure a complete hardware reset and reinitialization.

6. 6

   If the error recurs after these steps, contact the manufacturer's technical support with the exact error code and diagnostic data, or replace the safety PLC module.