PLC Fault Code Search Engine
Search engine for Siemens, Mitsubishi, and Omron error codes.
by KOEEDQuick Error Code Lookup
Select a common error code below or type one above to search the full database.
How to Find PLC Error Codes?
Siemens (S7-1200/1500)
Connect via TIA Portal, go to Online & Diagnostics > Diagnostic Buffer. Look for the Hex Event ID (e.g., 16# 0x2521).
Mitsubishi (FX/Q/L)
Use GX Works2/3. Go to Diagnostics > System Monitor. Check special register SD0 for the latest error code (e.g., 4100).
Omron (CJ/NJ)
For CJ2, check the 2-digit LED on the CPU (e.g., HE, E0). For NJ/NX, use Sysmac Studio Troubleshooting to find the 8-digit Event Code.
Frequently Asked Questions
How to clear a fatal error on Siemens S7-1200?
Fatal errors like 0x2521 require hardware correction first. After fixing the root cause (e.g., replacing a mismatched module), power-cycle the CPU or use TIA Portal's Online & Diagnostics > Diagnostic Buffer to acknowledge the error. If the error persists, check the backplane connector and firmware version.
What does the ERR LED flashing mean on Mitsubishi FX?
A flashing ERR LED on Mitsubishi FX series typically indicates a non-fatal diagnostic error. Connect GX Works2/3 and read the diagnostic buffer. Common causes include parameter mismatches (code 3300), communication timeouts, or memory checksum errors (code 6401). A solid ERR LED usually means a fatal hardware fault requiring CPU replacement.
Can I use this tool for Allen-Bradley CompactLogix errors?
Yes. This database includes common Allen-Bradley fault codes. Major fault codes like 0x1E (I/O Fault), 0x20 (Communication Loss), and 0x64 (Processor Fault) are covered. For the full fault log, connect via RSLogix/Studio 5000 and check Controller Properties > Major Faults.
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