Siemens Simatic S5 6ES5734-2BF00

Common defects

Common defects on a Siemens Simatic S5 6ES5734-2BF00 are:

Power Supply & Hardware

• No power / PLC not starting
• Blown fuses or power components
• Faulty internal power supply module
• Overheating due to poor cooling or fan failure
• Damaged capacitors or power circuits

Input & Output (I/O) Failures

• Digital inputs not responding
• Analog inputs showing incorrect values
• Digital outputs not switching or stuck
• Burnt or damaged relay / transistor outputs
• I/O modules not recognized or defective

Communication Problems

• No communication with HMI or SCADA
• Network issues (Profibus, Profinet, Modbus, Ethernet/IP, CAN, etc.)
• Serial communication (RS232/RS485) failure
• Fieldbus module malfunction
• Outdated or incompatible firmware causing errors

Memory & Software Issues

• Lost parameters or corrupted programs (EEPROM/Flash failure)
• PLC loses program after power-down
• Firmware corruption or software errors
• Faulty or empty backup battery
• Errors during upload/download of program

CPU & Processing Errors

• PLC freezes or resets unexpectedly
• CPU not responding to commands
• Error messages during startup or runtime
• Watchdog timer faults or internal CPU errors
• Synchronization issues with other modules

Mechanical & Physical Damage

• Broken PCB tracks or connectors
• Corrosion due to moisture or chemicals
• Contamination from dust, oil, or dirt
• Burnt components or discolored boards
• Poor solder joints (dry joints)

Other Failures

• Faulty display or diagnostic LEDs
• Non-functional buttons or keypad
• Expansion modules not detected
• Defective internal clock or timers
• EMI/RFI noise due to damaged filters