How to Resolve Siemens SINUMERIK Alarm 3000 Emergency Stop

Introduction

When an impending risk of a severe collision threatens to violently damage a high-precision workpiece or machine frame, triggering an emergency stop halts all drives instantly using maximum braking torque. However, the subsequent recovery phase is a high-risk operational window. Misunderstanding the machine's hardware interlocks—such as an unsecured workpiece, an unclamped chuck, or an overloaded turret motor—causes the Siemens NCK safety logic to actively lock out the mode group. An operator attempting to clear the emergency stop while a tool clamping timeout is active or an Alarm 700013 "Operation not allowed: chuck unclamped" is pending will find that the controller adamantly refuses to release the emergency stop state, stalling production and potentially causing unpredictable axis motions if hardware bypasses are attempted. Resolving this state requires a rigorous understanding of the SINUMERIK safety loop and its software handshakes.

Technical Summary

Signal / Code	Modal Group / Type	Applicable Brands	Critical Parameters	Primary Constraint
DB2600.DBX0.1 / DB10.DBX56.1 (Emergency Stop NCK/PLC Interface)	PLC / NCK Interface Signal	Siemens	MD36610 $MA_AX_EMERGENCY_STOP_TIME MD36620 $MA_SERVO_DISABLE_DELAY_TIME	MD36620 >= MD36610 & mechanical safety interlocks satisfied

Quick Read

• Identify Interface Addresses: Determine the active interface address based on system age—using DB2600 DBX0.1 for modern SINUMERIK 828D/840D sl, or legacy DB10 DBX56.1 for older series.
• Execute Dual Handshake: Pulse the "Acknowledge emergency stop" signal (DB2600 DBX0.2 / DB10 DBX56.2) and the "Reset" signal (DB3000 DBX0.7 / DB11 DBX0.7) simultaneously via the PLC logic to clear NCK active locks.
• Maintain Deceleration Control: Enforce the safety constraint MD36620 >= MD36610 to keep servo drives active under closed-loop control during the entire braking ramp length.
• Release Mechanical Latches: Manually rotate the physical emergency stop button counter-clockwise to release the hardware contactor before attempting any soft reset.
• Rectify Hardware Interlocks: Verify that the workpiece is secure, the chuck is fully clamped to prevent Alarm 700013, the tool clamping operation is complete (no Alarm 700011), and the turret motor is not overloaded (no Alarm 700022).
• Synchronize Spindle Encoder: Program SPOS=IC(0) in MDA mode immediately after a power-cycle to restore encoder reference before executing tapping retraction commands, preventing Alarm 014092.

Basic Concepts

In standard industrial manufacturing, emergency stop circuits represent the final layer of physical machine protection. The Siemens SINUMERIK emergency stop is structured as a hardware-linked PLC-to-NCK signal network rather than a standard software-based G-code instruction. When a safety barrier is breached or a physical button is pressed, the signal request is applied directly to the NCK interface, causing an immediate disable of the NC Start command and putting the mode group in an inactive state. Re-establishing normal operations requires satisfying both the hardware relays and the software logic layers. To ensure recovery can always be performed safely without loss of custom configurations, refer to Siemens SINUMERIK Data Backup and Archive Creation.

Deceleration dynamics are meticulously calculated by the SINUMERIK system during a critical fault. Instead of cutting electrical power to the drives instantly—which would cause heavy axes to coast unpredictably under kinetic inertia and damage the ball screws—the controller initiates a controlled deceleration. The system forces the drives to ramp down using maximum braking torque under closed-loop servo feedback. Once the drives reach a complete standstill, the controller safely disables the servo enables to lock the axes mechanically.

Safety interlocks represent the mechanical-to-electrical feedback loop that protects the workspace. Subroutine user alarms are mapped to physical switches that track variables such as workpiece clamping status, turret motor load, and tool changer position. If any of these mechanical safety conditions are unmet during the recovery phase, the PLC safety loop blocks the acknowledgment sequence. An operator must resolve these secondary hardware faults before the main emergency stop fault can be cleared from the screen.

Command Structure

The SINUMERIK safety architecture operates through specific interface data blocks (DB) that handle system states and diagnostic flags. The main emergency stop input request is mapped to the NCK/PLC interface, which monitors the physical status of the safety loop. When the safety loop is open, the active low state is processed, which triggers a complete lockout. The system monitors this state via NCK signal DB10.DBX106.1, which remains high as long as the emergency stop is active.

To successfully reset and clear this condition, the PLC program must execute a dual-signal handshaking sequence. This sequence involves setting the "Acknowledge emergency stop" signal and the "Reset" / "Mode group reset" signal simultaneously and holding them high until the NCK safety status bit is cleared. The interface addresses differ depending on the controller series, requiring engineers to map the correct bits during commissioning to prevent reset failure.

The control syntax and software interface addresses are structured as follows:

• DB2600.DBX0.1 / DB10.DBX56.1: Emergency Stop Input Request applied to the NCK/PLC interface.
• DB2600.DBX0.2 / DB10.DBX56.2: Acknowledge Emergency Stop Interface Signal.
• DB3000.DBX0.7 / DB11.DBX0.7: Reset / Mode Group Reset Signal.
• DB10.DBX106.1: Emergency Stop Active status indicator signal from NCK.

The critical machine parameters that control the deceleration and reboot timing are outlined in the table below:

Parameter	Description	Value Range / Constraint
MD36610 $MA_AX_EMERGENCY_STOP_TIME	Defines the length of the braking ramp for error states (axis-specific).	Time value (seconds)
MD36620 $MA_SERVO_DISABLE_DELAY_TIME	Defines the shutdown delay for the controller enable (axis-specific).	Must satisfy MD36620 >= MD36610
MD10088 $MN_REBOOT_DELAY_TIME	Establishes a delay time before rebooting if an emergency stop forces a system restart.	System-wide time value (seconds)

Brand Applications

Siemens

Siemens SINUMERIK controllers handle emergency stops using a highly deterministic safety architecture. The EMERGENCY STOP request is applied to the interface via DB2600 DBX0.1 (Emergency stop) on modern systems, or DB10 DBX56.1 on legacy configurations. When this bit drops, the NCK immediately halts axis motion and disables the mode group. To return the machine to a ready state, the operator must first release the physical emergency stop button. Then, the PLC program must coordinate a dual-signal handshaking sequence: the "Acknowledge emergency stop" signal (DB2600 DBX0.2 or DB10 DBX56.2) must be set simultaneously with the "Reset" signal (DB3000 DBX0.7 or DB11 DBX0.7) until the NCK resets the internal active bit (DB10 DBX106.1).

On specific compact configurations equipped with a SINAMICS V60 drive, the hardware limit switches can be encoded natively. The limit switches are wired directly to the drive as E-Key inputs 1LMTP, 2LMTP, and 3LMTP. When all of these inputs are active, the safety loop triggers a native emergency stop, dropping physical contactors and disconnecting terminal 65 via a physical relay. This instantly cuts the axis enables and forces a feed stop for all axes simultaneously to protect the mechanical hardware from overtravel collisions.

Brand Comparison

Series / Drive Combination	PLC Interface Address & Logic	Safety Features & Stop Behavior
SINUMERIK 840D sl / 828D	Uses modern PLC interface blocks DB2600 and DB2700 for safety handshake bits.	Software-configurable deceleration ramps with full integration into Siemens Safety Integrated functions.
Legacy SINUMERIK (840D powerline / 810D)	Utilizes legacy PLC interface bytes DB10 and DB11 to manage global machine signals.	Standard dual-signal handshake required; relies on basic machine data settings without advanced integrated safety networking.
SINAMICS V60 Compact Drive Series	Features hardwired safety limit switch encoding via active E-Key inputs (1LMTP, 2LMTP, 3LMTP).	Triggers a physical relay to disconnect terminal 65 (power enable) directly, executing an instantaneous hard feed stop across all axes.

Technical Analysis

The Siemens emergency stop architecture is engineered around the principle of controlled kinetic energy dissipation. In modern SINUMERIK 828D and 840D sl systems, safety is software-managed through modern DB2600 and DB2700 blocks, allowing detailed tracking of safety handshakes and seamless recovery. Legacy architectures utilizing DB10 and DB11 require identical handshaking but lack advanced Safety Integrated software analytics. When analyzing drive-level differences, the compact SINAMICS V60 drive stands out by bypassing PLC-only safety. It uses hardware-encoded limit switches (1LMTP, 2LMTP, and 3LMTP inputs) to drop terminal 65 natively. This cuts power directly at the drive terminal, serving as a robust hardware fallback when software handshaking fails.

Additionally, parameter settings dictate whether an emergency stop will protect or damage the mechanical assemblies. Parameter MD36610 $MA_AX_EMERGENCY_STOP_TIME defines the time window the axis has to execute its closed-loop deceleration ramp, while MD36620 $MA_SERVO_DISABLE_DELAY_TIME controls when the electrical servo enable is cut. In a properly tuned Siemens system, engineers must enforce the rule MD36620 >= MD36610. If MD36620 is incorrectly set lower than MD36610, the servo enable is cut prematurely while the axis is still moving at high velocity. The axis immediately drops closed-loop control and coasts under its own mechanical inertia, which can cause severe axis crashes or vertical head drops.

Program Examples

The following Siemens G-code examples demonstrate the mandatory spindle re-synchronization and retraction sequence required after an emergency stop power-cycle during a rigid tapping operation. Without these steps, attempts to execute retraction commands will trigger Alarm 014092. For a detailed guide on how origins and reference frames are re-established on CNC systems, consult the guide on CNC Zero Points Explained.

1. Spindle Absolute Encoder Re-synchronization

This command must be executed first to rotate the spindle slowly and locate the physical index mark of the absolute encoder, establishing the angular baseline.

; Spindle Absolute Encoder Re-synchronization Block
N10 SPOS=IC(0)          ; Rotate spindle to re-establish encoder synchronization

2. Synchronized Rigid Tapping Controlled Retraction

Once the encoder angular coordinates are restored, command the synchronized retract path along the Z-axis using the exact thread pitch and safe spindle speed.

; Synchronized Retraction Block
N20 G332 Z20 K1 S100     ; Execute rigid tapping controlled thread retraction

3. Complete Recovery and Reset Sequence

This integrated G-code program shows the entire sequence including rapid movement to a safe clearance plane after retraction and the program reset.

; Complete Tapping Retraction and Spindle Re-synchronization Program
N10 SPOS=IC(0)          ; Rotate spindle to re-establish encoder synchronization
N20 G332 Z20 K1 S100     ; Execute rigid tapping controlled thread retraction
N30 G90 G00 Z50          ; Rapid retract to safe clearance plane
N40 M02                  ; End of program and reset modal states

Dry Run Execution Procedure

Performing a dry run of the recovery routine prevents mechanical crashes by verifying encoder synchronization before the tool contacts the physical workpiece thread. Use the following step-by-step procedure:

1. Verify Mechanical Pre-requisites: Ensure that all physical faults are resolved, the emergency stop button is manually released, and the chuck is fully clamped (confirming no user alarms like Alarm 700013 are active).
2. Check Parameter Compliance: Confirm that the active machine data satisfies the safety inequality MD36620 >= MD36610.
3. Clear the Active Lock: Apply the simultaneous PLC handshake by pulsing the acknowledge bit DB2600.DBX0.2 and reset bit DB3000.DBX0.7 until the NCK emergency stop active status signal (DB10.DBX106.1) clears.
4. Position the Z-Axis: Move the Z-axis manually in JOG mode to a safe, clear position where there is at least 50 mm of clearance from the workpiece.
5. Select MDA Mode: Switch the controller to Manual Data Automatic (MDA) mode and input the recovery blocks.
6. Execute Spindle Sync (Block N10): Press Cycle Start. The spindle must rotate slowly to locate the physical index mark of the encoder and re-establish the absolute angular coordinate system.
7. Monitor Retraction (Block N20): Observe the Z-axis retracting smoothly at the programmed pitch (K1) and speed (S100), ensuring the spindle rotation and Z-axis linear feed are perfectly synchronized.
8. Verify Reset (Block N30): The program will terminate, resetting all modal parameters and returning the system to a normal, active ready state.

Error Analysis

Alarm Code	Trigger Condition	Operator Symptom	Root Cause & Practical Resolution
Alarm 3000 Emergency Stop	EMERGENCY STOP request applied to the NCK/PLC interface via DB2600.DBX0.1 or DB10.DBX56.1.	NC and mode groups become not ready; NC Start is disabled; active motion is halted via NC Stop.	A safety switch or physical button has been tripped. Verify physical safety contacts, release the hardware button, and execute a simultaneous PLC handshake setting the acknowledge bit (DB2600.DBX0.2) and reset bit (DB3000.DBX0.7).
Alarm 3001 Internal Emergency Stop	Internal safety system error or PLC handshake timing fault.	Functions identically to Alarm 3000; the NC locks out, and drives disable, but the alarm may be masked based on settings.	Internal software diagnostic fault or failed handshake. Check the PLC-to-NCK communication links and verify that safety relays are operating within timing specifications.
Alarm 014092 Axis is Wrong Axis Type	Attempting to run a thread retraction command (G332) in MDA mode after a safety power-cycle without spindle synchronization.	The NC rejects execution, and the retraction program aborts immediately, leaving the tool stuck in the thread.	The absolute correlation between the spindle encoder and Z-axis feed is lost post-E-stop. Program and run SPOS=IC(0) first to re-synchronize the spindle encoder before executing retraction blocks.
Alarm 700013 Chuck Unclamped	Workpiece clamping sensor is not active or chuck is in unclamped state during E-stop recovery.	The controller refuses to clear the active emergency stop state, keeping the mode group locked out.	Mechanical safety interlock fault. Manually clamp the chuck, verify that physical limit switches or proximity sensors are active, and clear the user alarm.
Alarm 700011 Tool Clamping Timeout	Tool clamping or unclamping cylinder fails to actuate within the designated PLC timer.	E-stop recovery is blocked; the hydraulic or pneumatic valves refuse to cycle, and the spindle remains locked.	Stuck solenoid valve, low hydraulic pressure, or sensor blockage by chips. Clean physical limit switches, inspect pressure gauges, and verify PLC timer settings.
Alarm 700022 Turret Motor Overload	Thermal overload relay or servo drive overload detection for the tool turret is triggered during a collision.	Turret index commands are ignored; the system blocks servo enable and prevents resetting the emergency stop.	Mechanical tool turret jam or thermal overload. Inspect the turret for collisions, reset the physical thermal overload switch in the electrical cabinet, and reset the drive.

Application Note

Failure to physically secure mechanical interlocks before attempting a system recovery will cause the SINUMERIK safety loop to persistently lock out the mode group, leaving the operator stranded with unresolved fault loops. If an emergency stop is triggered during a rigid tapping operation due to an impending tool collision, the machine will decelerate using maximum braking torque to prevent severe damage. However, upon rebooting, the absolute correlation between the spindle encoder and the Z-axis linear feed is lost. Attempting to execute an immediate retraction G-code block such as G332 without first commanding SPOS=IC(0) to re-synchronize the spindle encoder will instantly trigger Alarm 014092. This will fault the axis again, leaving the tool stuck in the thread, which often leads to the tool snapping and scrapping a high-value workpiece. Operators must guarantee that all mechanical faults—such as unsecured workpieces or tool turret jams—are resolved, and the physical emergency stop button is rotated counter-clockwise to release the contacts before the PLC handshaking sequence is initialized.

Related Command Network

• RESET: Initiates a mode group reset through DB3000.DBX0.7 or DB11.DBX0.7, which must be combined with the PLC acknowledgment signal to clear active NCK faults.
• SPOS: Commands spindle positioning to a specific angle or incremental step (such as SPOS=IC(0)) to re-synchronize the spindle encoder after an emergency stop power failure, acting as a crucial component of standard Spindle Commands.
• G332: Executes a controlled retraction motion for rigid tapping cycles, requiring full spindle encoder synchronization to prevent Z-axis feed mismatch.
• M02: Serves as the main program end command that resets local modal parameters and returns control to the start of the program after retraction is complete.

Conclusion

Resolving a SINUMERIK Alarm 3000 requires strict adherence to the dual-signal PLC handshake and complete verification of peripheral mechanical states. Maintaining axis-specific delay parameters like MD36620 >= MD36610 ensures axes decelerate safely under closed-loop control rather than coasting into hard stops. Prioritizing physical fault rectification and spindle re-synchronization (SPOS=IC(0)) ensures mechanical components remain undamaged and the system returns to an active, production-ready state without risking catastrophic tool breakage.

FAQ

Why does the SINUMERIK control remain locked in Alarm 3000 even after I have released the physical emergency stop button?

Releasing the physical button only restores the hardware contacts, but the controller requires a deterministic, dual-signal software handshake to clear the NCK-level active fault. The PLC logic must actively set the "Acknowledge emergency stop" signal (e.g., DB2600.DBX0.2 or DB10.DBX56.2) simultaneously with the "Reset" signal (DB3000.DBX0.7 or DB11.DBX0.7) to clear the state. Ensure your PLC logic is programmed to pulse both bits together; otherwise, the internal "Emergency stop active" bit (DB10.DBX106.1) will remain high, keeping the mode group locked out.

What causes Alarm 014092 when running a retract program in MDA mode after an emergency stop?

This alarm indicates that the controller has lost absolute synchronization between the spindle encoder and the Z-axis feed loop due to the emergency shutdown. Attempting to execute a rigid tapping retraction command (such as G332 Z20 K1 S100) in this unsynchronized state is blocked by the safety logic to prevent axis mismatch. To resolve this, you must program and execute a single spindle positioning command (SPOS=IC(0)) in MDA mode first, which spins the spindle briefly to locate the encoder's physical index mark and re-establish synchronization before running the retraction program.

How does the relationship between MD36620 and MD36610 prevent axis damage during a critical shutdown?

The parameter MD36610 $MA_AX_EMERGENCY_STOP_TIME specifies how long the drive has to decelerate to a complete stop, whereas MD36620 $MA_SERVO_DISABLE_DELAY_TIME defines the delay before cutting electrical power to the drive. Siemens safety rules dictate that MD36620 must be greater than or equal to MD36610. If MD36620 is set shorter than MD36610, the electrical servo enable is cut while the axis is still moving, causing the drive to coast without closed-loop control, which can lead to severe mechanical collisions or vertical axis drop under gravity. Regularly audit these parameters to guarantee they satisfy this inequality.