PROFIBUS/PROFINET: Fault on bus, slave/device

What does 380501 mean?

This alarm indicates that a fault has occurred on an assigned PROFIBUS/PROFINET slave or device, and its fault memory contents have been reported. The alarm provides the bus number, slave/device number, DO ID (%1), the fault code (%2), fault value (%3), and fault time (%4) of the device. This signifies a device-level fault on the bus, which requires consulting the device's documentation to prevent communication failures and system downtime.

• Short circuit or open circuit in the PROFIBUS (RS-485) bus cable or PROFINET (Ethernet) cable to the specific slave/device.
• Incorrect PROFIBUS termination resistor setting (e.g., missing, incorrect value 150 Ohm) on the identified segment.
• Duplicate PROFINET IP address or PROFIBUS address assigned to the faulted slave/device.
• Hardware failure of the identified slave/device's communication interface (e.g., burned port, faulty transceiver).
• Loss of power supply to the specific slave/device, causing it to drop off the bus and report a fault.

Click steps to track your progress.

1. 1

   1. Identify the exact bus number and slave/device address from the alarm message, then locate the physical device.

2. 2

   2. Visually inspect the PROFIBUS/PROFINET cable connected to the identified slave/device for damage, loose connections, or incorrect routing.

3. 3

   3. Use a PROFIBUS tester or network diagnostic tool (e.g., Wireshark for PROFINET) to check the signal quality and communication status of the specific device.

4. 4

   4. Verify the power supply voltage (e.g., 24VDC) at the terminals of the faulted slave/device using a multimeter.

5. 5

   5. Confirm that the PROFIBUS address dip switches or PROFINET IP settings on the device match the configuration in the PLC project.

6. 6

   6. Disconnect the identified slave/device from the bus and re-add it (if possible) to isolate if the fault lies with the device or the bus infrastructure.