This page covers FANUC DS alarms related to synchronization control, APC conditions, reference return, DCS-related settings, detector reference mark logic, PMC axis control, and servo motor spindle setup. These alarms are important because they often affect the machine’s ability to maintain axis coordination, establish reference position correctly, or recover normal position-related operation after power-on or maintenance work.
These alarm references apply to FANUC Series 0i-Model D and FANUC Series 0i Mate-Model D.
In practical maintenance work, this group of DS alarms often appears when synchronization settings are inconsistent, APC battery condition becomes critical, reference return cannot be completed normally, detector-related parameter relationships are incorrect, or PMC axis and spindle control settings are not aligned properly. At REACO CNC, we supply FANUC CNC parts, FANUC robot parts, Mitsubishi automation parts, and repair services for customers worldwide.
What These FANUC DS Alarms Usually Indicate
This section of the FANUC alarm list mainly relates to axis coordination, position establishment, and reference logic. In practical terms, these alarms may appear when synchronized axes do not meet allowed conditions, when the CNC cannot correctly maintain or restore the relationship between detector data and machine coordinates, or when the control detects invalid setup conditions in reference mark, detector, or DCS-related parameter structure.
Some alarms in this group are directly tied to APC battery and absolute position detection, while others are triggered when reference return is incomplete, synchronization conditions are not met, or certain detector combinations are not allowed. Because these alarms are closely tied to machine position integrity, they should be handled carefully before restarting production or re-establishing reference position.
Common Causes of FANUC Synchronization, APC and Reference Return DS Alarms
Typical causes include synchronization deviation exceeding limits, inconsistent detector combinations between axes, incomplete manual reference return, APC battery voltage falling too low, incorrect reference mark spacing parameters, invalid DCS-related settings, torque control parameter errors, or incorrect PMC axis control allocation.
In real service work, these alarms may also appear after battery replacement, detector replacement, machine movement with power off, parameter restoration, reconfiguration of synchronization control, or mistakes in spindle/PMC axis setup. Some alarms point to an actual hardware-side detector or battery issue, while others are caused mainly by parameter structure and configuration logic.
Full FANUC DS Alarm List: Synchronization, APC, Reference Return and DCS Errors
Table 1. Synchronization and Control Sequence Alarms
| Alarm Code | Alarm Message | Full Technical Content |
|---|---|---|
| DS0001 | Excessive synchronization error (position deviation) | During simple synchronization control, the torque command of the master axis and slave axis exceeded the value specified by parameter (No.8323). This alarm occurs only on the slave axis. |
| DS0003 | Feed axis synchronization control adjustment mode | The feed axis synchronization control function is in correction mode. |
| DS0004 | Maximum speed exceeded | The malfunction prevention function detected a command exceeding the maximum speed. |
| DS0005 | Maximum acceleration exceeded | The malfunction prevention function detected a command exceeding the maximum acceleration. |
| DS0006 | Execution sequence incorrect | The malfunction prevention function detected an illegal execution sequence. |
| DS0007 | Execution sequence incorrect | The malfunction prevention function detected an illegal execution sequence. |
| DS0008 | Execution sequence incorrect | The malfunction prevention function detected an illegal execution sequence. |
| DS0009 | Execution sequence incorrect | The malfunction prevention function detected an illegal execution sequence. |
| DS0010 | Illegal reference area | The malfunction prevention function detected an illegal reference area. |
| DS0011 | Illegal reference area | The malfunction prevention function detected an illegal reference area. |
| DS0012 | Illegal reference area | The malfunction prevention function detected an illegal reference area. |
| DS0013 | Illegal reference area | The malfunction prevention function detected an illegal reference area. |
| DS0014 | Machine lock detected during tool change | During tool change on the Z axis, machine lock is on. |
| DS0015 | Mirror image detected during tool change | During tool change on the Z axis, mirror image is on. |
| DS0020 | Reference return not completed | In manual reference return under tilted-axis control, or in automatic reference return after power-on before a first reference return has been executed, a reference return of the orthogonal axis was attempted before the tilted axis reference return had been completed. Perform reference return of the orthogonal axis after the tilted axis reference return is completed. |
| DS0021 | Start error (one-touch macro) | Program start cannot be accepted. Possible causes: 1) automatic operation stop signal *SP = 0; 2) alarm state is active; 3) SRN signal = 1. |
| DS0024 | Illegal UINT signal input | During movement to the restart machining position at dry run speed, an interrupt-type user macro instruction cannot be started. |
| DS0025 | Cannot execute G60 [M] | Unidirectional positioning cannot be executed because the mirror image state during pre-read of the program block and the mirror image state at execution start are different. Correct the program. |
Table 2. Serial DCL, Detector Combination and DCS Related Alarms
| Alarm Code | Alarm Message | Full Technical Content |
|---|---|---|
| DS0016 | Serial DCL: position tracking error | 1) The specification of parameters (No.1883, No.1884) is outside the allowable range. 2) When establishing the reference point, the distance between the current position and the reference point (in detection units) exceeded ±2147483647. Modify the current position or reference point to avoid this condition. |
| DS0017 | Serial DCL: reference point establishment error | During reference point establishment, the movement amount at FL speed exceeded the value set in parameter (No.14010). |
| DS0018 | Linear scale with reference mark: feed axis synchronization error setting | In feed axis synchronization control, one of the master/slave axes uses a linear scale with reference mark and the other uses a linear scale without reference mark. In this configuration, the reference point cannot be established unless the feed axis synchronization control selection signal SYNC<Gn138> or SYNCJ<Gn140> is set to 0. |
| DS0026 | Angular axis mismatch (D.C.S.) | In tilted-axis control, one of the tilted/orthogonal axes uses a linear scale with reference mark and the other uses a linear scale without reference mark. This configuration cannot be used. |
| DS0027 | Synchronized axis mismatch (D.C.S.) | In feed axis synchronization control, one of the master/slave axes uses a linear scale with reference mark and the other uses a linear scale without reference mark. In this configuration, the reference point cannot be established unless the feed axis synchronization control selection signal SYNC<Gn138> or SYNCJ<Gn140> is set to 1. |
| DS1448 | Illegal parameter (D.C.S.) | For a linear scale with reference mark, one of the following conditions applies: 1) absolute position detector is enabled (APC No.1815#5 = 1); 2) parameter (No.1821) for mark 1 interval or parameter (No.1882) for mark 2 interval is set to 0; 3) parameter (No.1821) is greater than or equal to parameter (No.1882); 4) the values of (No.1821) and (No.1882) differ by a factor of 2 or more; 5) the values of parameters (No.1883, No.1884) exceed the limit values. |
| DS1449 | Reference mark interval mismatch in parameter setting | For a linear scale with reference mark, the actual reference mark interval does not match the interval values set in parameters (No.1821, No.1882). |
Table 3. APC Battery, Absolute Position and Reference Return Alarms
| Alarm Code | Alarm Message | Full Technical Content |
|---|---|---|
| DS0300 | APC alarm: reference return required | Origin setting is required for the absolute position detector (relationship between the reference point and the counter value of the absolute position detector). Perform reference return. In some cases this alarm may occur together with another alarm. In that case, take action according to the other alarm as well. |
| DS0306 | APC alarm: battery voltage 0 | The battery voltage of the absolute position detector has fallen to a level too low to retain data, or the pulse coder is being powered on for the first time. If this alarm occurs even after power is turned on again, the battery or cable may be faulty. Replace the battery while the machine power is on. |
| DS0307 | APC alarm: battery voltage low 1 | The battery voltage of the absolute position detector has dropped to the replacement level. Replace the battery while the machine power is on. |
| DS0308 | APC alarm: battery voltage low 2 | The battery voltage of the absolute position detector has previously fallen to the replacement level, including during power-off. Replace the battery while the machine power is on. |
| DS0309 | APC alarm: reference return cannot be executed | An attempt was made to perform origin setting of the absolute position detector by MDI when the reference point could not be established. Manually rotate the motor more than one full revolution, temporarily turn off the power to the CNC and servo amplifier, and then perform origin setting of the absolute position detector. |
| DS0310 | Not at reference point [manual intervention and return] | Return to the position before intervention could not be completed. The position may have shifted during return due to machine lock or mirror image. After reset, restart operation from an appropriate machining position. |
| DS0405 | Not returned to reference point | In automatic reference return, the specified axis did not return correctly to the reference point at the end of positioning. Perform reference return from a position located two or more motor revolutions away from the reference point return start position. This may also be caused by position deviation less than 128 after deceleration dog activation, or by insufficient pulse coder voltage or pulse coder defect. |
| DS1450 | Reference return not completed | With parameter ZRN (No.1005#0) = 0, reference return to the first reference point (07h) was commanded before one manual reference return had been performed after power-on. |
| DS1933 | Reference return required (synchronization, composite, overlap) [T] | In an axis under synchronization, composite, or overlap control, the relationship between mechanical coordinates and absolute or relative coordinates has deviated. Perform manual reference return. |
Table 4. Torque Control, PMC Axis and Servo Motor Spindle Related Alarms
| Alarm Code | Alarm Message | Full Technical Content |
|---|---|---|
| DS1184 | Torque control parameter error | In torque control, the parameter setting is incorrect. The torque constant parameter is 0. |
| DS1451 | PMC axis control command error | The machine is in a state where PMC axis control cannot be executed. |
| DS2003 | Servo motor spindle parameter setting error (PMC axis control) | A spindle control axis based on a servo motor has been set as a PMC-controlled axis. |
| DS2005 | Speed gain automatic adjustment in progress | Automatic operation cannot be started while speed gain automatic adjustment is in progress. Confirm that automatic adjustment has been completed before starting automatic operation. |
Practical Inspection Notes
When this group of DS alarms appears, the first step is usually to determine whether the problem is related to synchronization structure, APC battery and absolute position retention, reference return sequence, or detector/reference mark parameter consistency. In many cases, the control is not reporting a simple one-time disturbance but a condition that affects the machine’s ability to trust its coordinate relationship.
For APC battery alarms, it is important to replace the battery correctly while the machine power is on, as indicated by the technical description. For reference return alarms, practical checks usually include machine coordinate state, whether reference return has already been completed after power-on, detector health, and whether the machine was moved abnormally or with power off. For DCS and linear scale related alarms, parameter combinations and actual detector structure should be checked together, because some detector combinations are not allowed under the specified control mode.
REACO CNC Support
REACO CNC supplies FANUC CNC parts, FANUC robot parts, Mitsubishi automation parts, and repair services for customers worldwide. If your machine is showing FANUC DS alarms related to APC battery conditions, synchronization control, reference return, linear scale settings, or PMC axis control, we can support your spare parts sourcing and industrial repair requirements.
With 34 years of industry experience, REACO CNC supports global customers with worldwide shipping, tested industrial parts, and practical repair solutions for FANUC and Mitsubishi systems.
FAQ
What does a FANUC DS alarm usually mean?
It usually means the control detected a synchronization issue, APC-related condition, reference return problem, detector parameter inconsistency, or another position-establishment related abnormality.
What should be done when DS0306, DS0307 or DS0308 appears?
These alarms indicate APC battery voltage problems. The technical guidance says the battery should be replaced while the machine power is on.
What does DS0300 indicate?
It indicates that origin setting or reference return is required for the absolute position detector.
Why can DCS-related alarms appear?
They can appear when detector types, reference mark settings, or related parameter combinations are inconsistent or not allowed for the configured control mode.
Which machines does this reference apply to?
These alarm references apply to FANUC Series 0i-Model D and FANUC Series 0i Mate-Model D.
Reference Source: Beijing FANUC. This article is based on technical documentation provided by Beijing FANUC.
For More Fanuc CNC repair Cases and technical articles, please back to Fanuc Technical Support Center.
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