Clearing the fault, changing PLC timing, or tuning the motion profile may hide one cycle of the symptom, but none addresses configuration values that are reloaded when the controller enters Program mode or accepts a download. A repeatable fault at that transition points first to reinitialization and stored actuator parameters, not to a suddenly higher mechanical load.
Why do the usual fixes fail?
Resetting the fault only clears the latch. It does not correct the value that will be restored during the next communication or controller-state transition. Repeating the reset in PLC logic therefore converts a diagnostic into a recurring automatic event.
Adding delays around the output command is also incomplete. A download can reset the PLC output image, interrupt the EtherNet/IP connection, and restart configuration handling. A delay may postpone motion, but the actuator will fault again if its active inward or outward current limit has become 0 A or another invalid value.
Changing speed or ramps without first reading the active configuration mixes cause and effect. Tuning does not fix wiring or startup data. Likewise, replacing motion logic with a function block will not repair a parameter set restored by another device in the signal chain.
What creates the overcurrent fault at reinitialization?
The PLC supplies a motion command through the EtherNet/IP connection. The interface converts that command into actuator behavior, while stored limits constrain speed, acceleration, deceleration, and allowable motor current. The final element sees both the command and those constraints.
If an IO-Link master is part of the architecture and Backup & Restore is enabled, the master can reapply its stored parameter set when the connection or device is reinitialized. Undefined defaults can overwrite usable actuator settings. The critical example is a current limit restored as 0 A: the next attempt to move immediately exceeds the configured limit even though the mechanism has not developed a new load.
The reported architecture is ambiguous because the control connection is described as EtherNet/IP while the proposed storage mechanism is IO-Link. Trace the physical and logical path before changing anything. If the PLC communicates directly with the actuator interface and no IO-Link master exists, inspect the EtherNet/IP interface's own initialization and persistence mechanism instead; an IO-Link data-storage correction cannot apply to a master that is not installed.
Which values should be measured before adjustment?
Look at the trend first. Capture the transition from Run to Program, the download, and the first movement request after returning to Run. Correlate the PLC output data, actuator status, fault indication, and configured limits. Include actual current only if the interface exposes it; a fault bit alone does not prove that motor current physically increased.
| Signal or value | Source | Wrong-value symptom |
|---|---|---|
| Motion command | PLC EtherNet/IP output data | An unintended nonzero command can request motion immediately after reconnection. |
| Inward current limit | Stored actuator or master configuration | A restored 0 A or invalid value causes inward motion to trip immediately. |
| Outward current limit | Stored actuator or master configuration | A restored 0 A or invalid value causes outward motion to trip immediately. |
| Speed | Actuator configuration | An undefined or invalid value produces behavior that differs from the commissioned motion profile. |
| Soft-start and soft-stop ramp times | Actuator configuration | Missing or invalid ramp data changes how the final element receives the motion demand. |
| Fault and status data | Actuator input data to the PLC | The transition timestamp shows whether the fault appears during reconfiguration or only after motion begins. |
Record parameter values twice: immediately before the mode change and immediately after communication returns. A changed current limit identifies parameter restoration. An unchanged, valid limit redirects the investigation toward output sequencing, wiring, mechanical load, or a genuine current event.
How should the stored configuration be corrected?
- Place the mechanism in a condition where unexpected movement cannot create a hazard, then inhibit the PLC motion request.
- Identify every device between the PLC and actuator. Determine whether an IO-Link master performs Backup & Restore or whether the EtherNet/IP interface retains the configuration itself.
- Save the working parameter values before editing them. Record inward and outward current limits, speed, soft-start time, and soft-stop time.
- Connect with
Actuator Connect. The reported setup used the proprietary257901 Y IO USBLIN06cable; confirm the required connection method intechline-ethernetip-interface-user-manual-eng.pdffor the installed interface. - Enter valid application values for both motion directions and the motion profile. Select limits from the actuator documentation and measured load; do not substitute an arbitrary nonzero current value merely to suppress the fault.
- Store the corrected data in the component that will be authoritative after reinitialization. With IO-Link Backup & Restore enabled, its stored dataset must contain the commissioned values rather than blank or zero defaults.
- Reconnect the control path with the motion command held at stop. Read back every edited value before permitting movement.
How is the correction verified?
Test the same events that previously reproduced the failure. Start with a Run-to-Program-to-Run transition, then perform a controlled PLC download. After each event, read back the current limits, speed, and ramp values before issuing a command.
Command a short inward move and a short outward move separately. Confirm that the expected direction moves, the fault remains clear, and the PLC status corresponds to the command. Compare the actual current trend if available against the configured directional limit. Repeat the transition several times; one successful restart does not prove that data storage is deterministic.
If the values remain correct but the fault occurs only when motion starts, isolate command sequencing from physical load. Test whether the output image briefly requests motion during reconnection, inspect power and motor connections, and check the mechanism for binding. A stationary overcurrent fault with a valid limit and no motion request follows a different diagnostic path from a trip that occurs under load.
Which pitfalls make the fault return?
Correcting only one direction leaves the opposite current limit vulnerable. Editing the actuator while an upstream master retains an older dataset allows that master to overwrite the repair on the next initialization. Conversely, changing only the master's record without confirming the device readback can leave the active actuator values unchanged until another restore cycle.
Do not treat PLC output reset and actuator parameter reset as the same event. The output image defines what motion is requested; configuration defines how the actuator interprets and limits that request. Trend both sides of the signal chain, and keep the motion command inhibited until configuration readback is complete.
FAQ
Why does the LINAK LA25 report overcurrent after a PLC download?
The download interrupts or reinitializes the control path. If stored configuration restores an inward or outward current limit of 0 A or another invalid value, the next motion request trips immediately.
Why does clearing the overcurrent fault not solve it?
Fault reset clears the indication but leaves the restored parameter set unchanged. The same value returns or remains active at the next Program-mode transition or download.
Why should I check for an IO-Link master on an EtherNet/IP system?
EtherNet/IP may be the PLC-facing network while an intermediate master manages device parameters. If no IO-Link master exists, inspect configuration persistence in the installed EtherNet/IP interface instead.
Why do I need Actuator Connect instead of changing PLC logic?
Actuator Connect accesses actuator configuration such as directional current limits, speed, and ramp times. The reported setup required cable 257901 Y IO USBLIN06; PLC logic cannot correct a separate stored dataset by itself.
When should I stop troubleshooting and contact official support?
Stop if valid parameters read back unchanged, the PLC sends no motion request, and the actuator still reports overcurrent, or if the required configuration fields and storage owner cannot be identified. Preserve the before-and-after trend, parameter readback, network topology, and interface details, then escalate to LINAK through its official support channel. Do not continue repeated motion tests if wiring, mechanical binding, or a genuine high-current condition remains possible.