liminfoSchneider Electric Fault Code Reference
Schneider Electric Modicon PLC & Altivar drive fault code reference with causes and solutions
About Schneider Electric Fault Code Reference
The Schneider Electric Fault Code Reference is a searchable database of error codes covering six categories of Schneider Electric automation equipment: Modicon M340/M580 PLCs (CPU_ERR, MEM_ERR, CONF_ERR, WDG_ERR), Altivar ATV320/ATV600 variable frequency drives (OCF, OHF, OSF, OLF, ObF, USF), EtherNet/IP and serial communication modules, power supply diagnostics, I/O module faults, and TeSys motor starters with protection devices.
Each fault code entry includes a detailed root-cause analysis listing 3-5 common causes and a numbered step-by-step resolution procedure with 5 specific actions. The Altivar drive section covers overcurrent (OCF), overtemperature (OHF), overspeed (OSF), phase loss (OPF1), communication loss (SLF1, CnF), internal fault (InFt), and DC bus voltage faults (ObF, USF).
This reference is built for automation engineers, electrical technicians, and maintenance teams who need to quickly diagnose and resolve equipment faults in the field. All data is stored locally in your browser, enabling offline access on tablets and phones even in industrial environments without internet connectivity.
Key Features
- Modicon M340/M580 PLC fault codes: CPU errors, memory faults, configuration mismatches, watchdog timeouts, and redundancy failures
- Altivar ATV320/ATV600 drive faults: OCF, OHF, OSF, OPF1, SLF1, InFt, CnF, OLF, ObF, USF with detailed troubleshooting
- EtherNet/IP, Modbus RTU/TCP, CANopen, PROFIBUS DP communication error diagnostics
- Power supply fault codes: overvoltage, undervoltage, overload, overtemperature, 24V DC short, and redundant supply failures
- I/O module diagnostics: range errors, wire breaks, short circuits, configuration mismatches, and high-speed counter faults
- TeSys motor protection: overload, short circuit, ground fault, PTC thermistor, phase loss, and locked rotor detection
- Each fault code provides numbered cause analysis and step-by-step resolution procedures
- Filterable by 6 equipment categories with full-text search across all codes
Frequently Asked Questions
What does Schneider Altivar fault code OCF mean?
OCF (Overcurrent Fault) indicates the drive output current exceeded the instantaneous overcurrent trip threshold. Common causes include motor cable short circuit or ground fault, rapid acceleration, and motor-drive capacity mismatch. Resolution involves measuring motor cable insulation resistance, checking motor winding phase-to-phase resistance, increasing acceleration ramp time (ACC), and verifying the current limit (CLI) parameter.
How do I troubleshoot Schneider Modicon PLC CPU_ERR?
CPU_ERR is a processor exception typically caused by watchdog timeout from excessive program scan time, infinite loops, or hardware errors. Use Unity Pro/EcoStruxure Control Expert to monitor scan time, optimize program logic by removing unnecessary loops, check the watchdog timer setting in PLC Properties > Task, and update CPU firmware. If persistent, consider CPU module replacement.
What causes Altivar drive ObF (DC bus overvoltage)?
ObF occurs when the DC bus voltage exceeds the limit, usually during motor deceleration when regenerative energy raises the bus voltage. It can also be caused by high supply voltage or a missing/faulty braking resistor. Increase the deceleration ramp time (DEC), install or verify the braking resistor, enable DC bus auto-adapt deceleration, and check supply input voltage.
How do I resolve EtherNet/IP communication timeouts (ETH_ERR) on Schneider PLCs?
ETH_ERR indicates communication loss between the EtherNet/IP scanner and adapter. Check Ethernet cables and RJ45 connectors, verify IP address and subnet mask settings, perform a ping test, check network switch port LEDs, and adjust the RPI (Requested Packet Interval) settings. Also verify there are no IP address conflicts on the network.
What is TeSys OL and how do I reset it?
TeSys OL is a motor overload trip from the thermal overload relay (LRD/LR9). It triggers when motor current exceeds the set value for an extended period or during single-phase operation. Verify the relay current setting matches motor rated current, measure actual motor current, check 3-phase balance for phase loss, manually press the RESET button after removing the overload cause, and inspect mechanical load.
How do I fix Schneider Altivar InFt (internal fault)?
InFt indicates an internal hardware error in the drive, including possible IGBT module or control board damage. Power OFF the drive for 60 seconds then power ON. If InFt persists, attempt a STOP/RESET. Check and update drive firmware. InFt is not field-repairable and typically requires Schneider service center assistance or drive replacement.
What causes Modicon PLC CONF_ERR (configuration mismatch)?
CONF_ERR occurs when the hardware configuration in EcoStruxure Control Expert does not match the actual rack module layout. This happens after module replacement without configuration update or when a wrong module is installed. Compare the HW catalog with the actual rack, install correct modules, and re-download the configuration to the PLC.
Is this Schneider Electric fault code reference free?
Yes, this reference is completely free with no usage limits, no account required, and no software installation needed. All 55+ fault codes across 6 categories are instantly searchable. The tool runs entirely in your browser, making it suitable for offline use on the factory floor.