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SIMATIC S7-400 / S7-400H / S7-400F /FH: Networking Lost, Starting Within Halt Mode

Hi all....In our Electric Rope Shovels it´s installed a CPU 416-2 DP. After a Power Lost condition in the machine and when the PLC restarts again, PLC starts in STOP mode, therefore we always ended with a Comunication Lost failure and the machine in stopped condition.
¿Do you have any idea about what is generating this problem? or ¿Do you have any idea on how to solve this situation?
Regards, Juan.

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Answers(1)

PLC Starts in STOP Mode After Power Loss - CPU 416-2 DP

Dear Juan,

The issue of your CPU 416-2 DP starting in STOP mode after a power loss is often related to the configured restart mode and/or communication settings.

Here are potential causes and solutions:

  • Restart Mode: Verify the restart mode setting in the PLC configuration (likely set to "Warm Restart" or similar). Try configuring it to "Cold Restart" to ensure a full initialization.
  • Communication Parameters: Confirm the correct communication parameters (baud rate, node address, etc.) are configured for the PROFIBUS DP network. A mismatch can cause communication failure during startup.
  • PROFIBUS DP Master/Slave Configuration: Ensure the PROFIBUS DP master device is correctly configured to recognize and communicate with the PLC after a restart.
  • Hardware Issues: Although less common, check the power supply and wiring to the PLC and PROFIBUS DP interface for any instabilities.

For detailed information and troubleshooting steps, please refer to the following resources on SiePortal:

If the problem persists, please provide the PLC program (OB1, OB100), hardware configuration, and details of the PROFIBUS DP network for further assistance.

Sincerely,

Siemens Self Support

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