Allen-Bradley PowerFlex 525 F073 — What It Means
The F073 fault on the PowerFlex 525 means EN Net Loss. The drive has detected that the control communication path through its embedded EtherNet/IP adapter has been interrupted. This is not the same as the DSI network loss (F071) or option card network loss (F072). The drive faults because the EtherNet/IP connection to the scanner or controller is no longer valid, or the drive no longer sees the expected network communications.
The fault typically appears when something has disrupted the Ethernet link between the drive and the PLC or network scanner. Rockwell’s fault table lists cycle power, check cabling, verify EtherNet/IP settings, and check the external network as the standard recovery actions. The drive can also be configured to fault on comm loss through parameter C125 (Comm Loss Action), so the fault may appear even if the application does not require such aggressive behavior.
Before You Replace Anything
Technicians sometimes replace the entire drive or control module when the fault is simply a loose RJ45 plug or a failed network switch port. Always verify the physical cable, link LEDs, and external network status before condemning the drive hardware.
Common Causes
- Loose, damaged, or intermittent Ethernet cable or RJ45 connector (~40%) The physical Ethernet cable connection can work loose over time from vibration, or the cable itself may have internal breaks or poor crimps that cause intermittent link loss.
- Network switch issue or network outage (~25%) The upstream Ethernet switch port may fail, the switch itself may lose power, or a network-wide outage can drop the drive’s connection to the scanner.
- PLC or scanner stopped or connection path lost (~20%) If the controller or EtherNet/IP scanner stops running or the configured connection is deleted or faulted, the drive will detect loss of the control path and throw F073.
- Incorrect EtherNet/IP settings or IP address conflict (~10%) Incorrect IP addressing, subnet mask, or scanner configuration can prevent the drive from maintaining a valid EtherNet/IP connection, or an IP conflict can knock the drive off the network.
- Comm Loss Action parameter too aggressive for the application (~3%) Parameter C125 (Comm Loss Action) may be set to fault the drive on any loss of communications, even when the process could tolerate a temporary network interruption without stopping.
- Failed embedded EtherNet/IP adapter or control module (~2%) In rare cases the drive’s own embedded EtherNet/IP hardware can fail, though this is much less common than external network and cabling issues.
Quick Diagnosis
Answer these to narrow it down fast.
Do the link LEDs light up on both the drive Ethernet port and the switch port?
No: No link means a cable, connector, or port problem. Reseat the cable, swap the cable, or try a different switch port.
Can you ping the drive's IP address from the network?
No: The drive is not reachable on the network. Check the IP address, subnet mask, cable, and switch port assignment.
Does the fault clear after reseating the Ethernet cable and cycling power?
No: The fault persists. Check the external network, controller configuration, and consider the embedded EtherNet/IP adapter or control module as a hardware fault boundary.
Step-by-Step Fix
- Confirm the fault code on the drive display or diagnostic log is F073 (EN Net Loss).
- Inspect the Ethernet cable at both the drive and switch ends, reseat the RJ45 connectors firmly, and look for visible damage or kinks.
- Check the link LEDs on the drive Ethernet port and the switch port to verify a physical layer handshake is present.
- Verify the external network by confirming the switch is powered on, the PLC or scanner is running, and the drive IP address is reachable on the network.
- Review the EtherNet/IP configuration in both the drive and the controller, checking IP address, subnet mask, and scanner connection setup.
- Cycle power on the drive after correcting any cable or network issue, as this is Rockwell’s first listed recovery action.
- If the fault persists, evaluate parameter C125 (Comm Loss Action) to make sure the drive behavior on comm loss matches the application requirements, and consider the embedded EtherNet/IP adapter or control module as a hardware failure if all external checks pass.
Parts Often Needed
| Part | Notes |
|---|---|
| Cat5e or Cat6 Ethernet patch cable | Amazon | Replace if the existing cable shows damage, intermittent connection, or failed link. |
| PowerFlex 525 control module | Amazon | Only if the embedded EtherNet/IP adapter is confirmed failed after all network and cabling checks. |
When to Call a Pro
Call a controls technician or industrial electrician if you are not familiar with EtherNet/IP networks, PLC programming, or drive parameter configuration. The fault itself does not involve dangerous high voltage, but diagnosing network issues requires knowledge of IP addressing, switch configuration, and scanner setup in the controller. If you have already reseated cables, verified link LEDs, and confirmed the switch and controller are running but the fault still appears, a professional can check the EtherNet/IP connection programming, parameter C125, and determine whether the drive’s embedded adapter has failed. Also call a pro if the drive is part of a larger automated system where incorrect troubleshooting could disrupt production or create a safety hazard.
Rough cost: A pro service call runs about $100-250 for service call and cabling/network troubleshooting; higher if drive replacement is needed.