In CNC machines with multiple speed ranges (e.g., high-speed and low-speed windings), the system uses electrical contactors to switch between these ranges. The 7115 alarm signals that the control system did not receive the expected feedback signal from these switching contactors, indicating they are not in the commanded state. Primary Causes
A small battery unit supplies continuous power to the encoder memory when the CNC machine is powered down.
Before touching the CNC controller, open the electrical cabinet and look at the spindle amplifier module. If you see , it confirms the issue is with the speed switching contactors . 2. Inspect the Spindle Winding Contactors
Periodically check the liquid-tight seals on motor terminal boxes to ensure coolant cannot seep inside. fanuc 7115 alarm
Test your servo and spindle motor insulation yearly to catch degradation before it blows the amplifier.
Does the alarm trip or only during a heavy cut / axis movement ?
If the switches are functional, the fault lies inside the controller cabinet. In CNC machines with multiple speed ranges (e
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The CNC controller commands a speed change, but the PMC (Programmable Machine Controller) does not receive confirmation that the gear or winding has switched within the allotted time.
When the FANUC 7115 alarm occurs, you may notice the following symptoms: Before touching the CNC controller, open the electrical
Verify that the contactors for the spindle winding switch are physically moving and that their contacts are not burnt or pitted.
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The most critical first step is to confirm the alarm number. Double-check your CNC controller's display. The alarm number 7115 might be accompanied by a prefix like "SV" (Servo), "PS" (Power Supply), or "SR" (Spindle). This prefix is a vital clue that points you directly to the source of the issue.
The robot was commanded by the software program to move to a position outside its allowable physical workspace.
If the 7115 alarm occurred because the battery went completely dead while the machine was powered off, replacing the battery will clear the alarm, but you will likely face a follow-up alarm: .
