Internal Error

What does 8500 mean?

A critical, unspecified internal error has occurred within the Safety PLC, pointing towards a fundamental hardware or firmware fault. This compromises the PLC's ability to execute its safety program reliably and can lead to unexpected machine states or failure to perform safety actions. This error requires immediate attention to maintain system safety.

• Corrupted safety PLC firmware due to unexpected power cycling or failed update process.
• Faulty internal memory (RAM or Flash) module within the safety PLC hardware, leading to data integrity issues.
• Defective CPU or application-specific integrated circuit (ASIC) on the safety PLC's mainboard.
• Over-temperature condition detected by internal sensors, indicating a cooling system failure or environmental issue exceeding limits (e.g., >55°C).
• Internal power supply unit (PSU) failure within the safety PLC module, causing unstable internal voltage rails (e.g., 3.3V, 5V).

Click steps to track your progress.

1. 1

   Record the exact fault code, any sub-codes, and associated diagnostic data displayed on the PLC or via engineering software.

2. 2

   Verify the input supply voltage to the safety PLC module at terminals L+ and M (24VDC) using a calibrated multimeter to confirm it is within specified range (e.g., 21.6-28.8VDC).

3. 3

   Perform a cold reboot of the safety PLC by cycling its main power supply OFF for a minimum of 30 seconds, then reapply power.

4. 4

   Attempt to upload the diagnostic buffer and safety program to the engineering software to identify any further details or program inconsistencies.

5. 5

   Check the ambient temperature around the safety PLC and ensure it is within the manufacturer's specified operating range. Verify adequate air circulation around the module.

6. 6

   If the error persists after power cycling and diagnostics, replace the safety PLC module with a known good spare of the exact same part number and firmware revision.