SINUMERIK 802D sl: Resolving NO WRITE ACCESS on Turning

Problem Summary

The SINUMERIK 802D sl turning controller returns the alarm NO WRITE ACCESS when the operator attempts any of the following actions from the operator panel:

• Entering a measured workpiece value in the Work Offsets table (G54–G59 zero offsets, settable zero offsets G54.1 P1..P48, or the wear and basic offset columns).
• Touching off a tool in JOG mode using the Measure Tool softkey (tool length and tool radius in the tool list or magazine list).
• Creating, modifying, or saving an NC part program in the Program Manager directory (MPF.DIR, SPF.DIR, CMA.DIR, or the manufacturer-specific work directories).

The message appears the moment the operator presses INPUT or the Save softkey, and the change is discarded silently. The condition affects work offsets, tool offsets, and the program directory simultaneously, which is the diagnostic fingerprint of an insufficient operator access level rather than a file-system or NCK fault.

SINUMERIK 802D sl Access-Level Architecture

The 802D sl implements a seven-tier password protection model that gates write operations on the HMI. Each access level has a default password defined by Siemens and a typical use case in the field:

The 802D sl allows the current access level to be raised and lowered at any time through the password dialog. The active level is shown in the upper-right corner of the HMI as a numeric indicator (for example, AC: 3). It is volatile and resets to the key-switch position after the next NCK power-up.

Writing to work offsets, tool offsets, and part programs requires at least level 3 (User) by default. If the active level is 4 (operator) or below, the NCK rejects all write requests and returns the NO WRITE ACCESS alarm. The reference manual is the Siemens Industry Online Support documentation set for the SINUMERIK 802D sl, which details the access level assignments and the machine data that control them.

Root Cause of the NO WRITE ACCESS Alarm

Three field-proven root causes account for almost every occurrence of this alarm on a turning installation:

1. Default operator position. The key-switch is in the operator position and the password dialog has never been invoked after power-on. The active level is 4, which permits run-time actions only.
2. Service-level lockout. The machine builder has configured the work-offset and program areas to require a level above the default user level. The customer password is accepted by the dialog but rejected by the protected area, which still raises NO WRITE ACCESS.
3. Password replaced by the builder. The default CUSTOMER password has been replaced by a builder-specific string and the operator is using the default. The dialog appears to accept the entry but the level is not raised, because the password does not match.

A fourth, less common cause is a write-protected file system. On the 802D sl, the active part program directory is on the compact flash card and a corrupted CF card can present the same alarm. To distinguish a level issue from a file-system issue, attempt to write to a tool offset (which lives in NCK SRAM) and a part program (which lives on the CF card). A file-system fault will succeed on the tool offset and fail on the part program; an access-level fault will fail on both.

Resolution: Setting the Access Password via the System Screen

The 802D sl exposes the password dialog through two keyboard shortcuts. Both reach the same system screen on every 802D sl panel variant:

• ALT + N — the standard shortcut from the OP 010 / OP 010C / OP 010S operator panels.
• SHIFT + ALARM — alternate shortcut on panels where the ALT key is not bound to a key, or on early OP 010C revisions.

When the dialog appears, the operator enters the level-3 password. On a default installation, the password is the literal string CUSTOMER. On builder-customized installations, the password is the seven-character string installed at commissioning. Field notes commonly report the masked form S*****E, which is the SERVICE-level password used by the builder to grant service technicians write access during installation. The S*****E mask is typical of the builder's commissioning string, not the default CUSTOMER.

Step-by-step procedure:

1. Power on the controller and wait until the HMI reaches the main operating area. Confirm that no program is running and that no channel is in reset, M00, or M02.
2. Place the machine in a safe state: spindle stopped, axes referenced, hydraulic OK. Open the door interlock if required for safe access.
3. Press ALT + N on the operator panel. The Set Password dialog appears with a single password input field.
4. Enter the level-3 password. Use the default CUSTOMER unless the builder has supplied a replacement string. Press INPUT or the Enter key.
5. Confirm the new access level in the upper-right HMI bar. The indicator should read AC: 3 after a successful entry.
6. Navigate to the desired area (Work Offsets, Tool Offsets, or Program Manager) and repeat the write attempt. The NO WRITE ACCESS alarm is replaced by the standard Save OK confirmation.

If the dialog rejects CUSTOMER with the indicator still reading AC: 4, the builder has changed the password. Request the active string from the machine builder's documentation set or from the service organization. Do not attempt to derive the password from machine data, as the 802D sl stores passwords as encrypted hashes and only the HMI dialog accepts entries.

Alternative: Configuring Write Access Through Machine Data

If the customer password has been forgotten, or if the service organization needs to lock or unlock specific write functions, the access-level assignments are controlled by machine data on the 802D sl. The relevant data blocks are documented in the SINUMERIK 802D sl lists manual and equipment manual on the Siemens Industry Online Support portal.

To modify machine data, the operator must first enter the SERVICE-level password (default EVENING) at the system screen. The procedure is:

1. Press ALT + N and enter the SERVICE password. Confirm AC: 2 in the HMI bar.
2. Press MENU SELECT and navigate to Setup → Password → Machine Data. On some 802D sl panel variants the menu is Setup → Commissioning → Machine Data.
3. Use the Search field to locate the MD by number (for example, MD 51072).
4. Modify the value, then press the OK or Accept softkey to write back to the NCK.
5. Perform an NCK Reset to activate the change. Some MDs (typically those marked with the reset attribute) require a full NCK restart (power cycle) to take effect.

Verification Procedure

After setting the access level, perform a three-part verification to confirm that all three affected areas now accept writes:

1. Work offset write test. Open Offset → Work Offsets, select a known G-code offset (for example, G54), and enter a value in the Wear column. Press INPUT. The value must remain on screen after a softkey change to another offset and back. Power-cycle the controller to confirm the value is persisted in SRAM.
2. Tool offset write test. Switch the mode switch to JOG. Select a tool in the tool list, then run the Measure Tool softkey. Touch a known reference (workpiece zero face, calibrated probe) and confirm. The measured length must be written to the tool's length register and survive a power cycle.
3. Part-program save test. Open the Program Manager, select an existing part program, press Open, add a single comment line, and save with Save. The Save OK message must appear and the change must persist.

If any of these still returns NO WRITE ACCESS, the active level is still too low. Re-open the password dialog and confirm the level indicator. If the level is correctly set but the alarm persists, the machine data has gated the specific function to a higher level. The service organization must inspect MD 51072 and the related parameters.

Related Fault: Spindle Emergency Stop at 800–900 RPM

Field reports on 802D sl turning installations frequently include a second fault: the spindle runs for a short time, then stops automatically as RPM climbs into the 800–900 range. The stop is accompanied by an emergency-stop indication and a Hydraulic Pressure Low alarm on the HMI. This is a separate interlock issue and is not caused by the access-level settings, but it shares the same commissioning phase and should be addressed in the same visit.

The spindle drive ramps speed while monitoring a hydraulic OK signal. As RPM increases, hydraulic demand rises from the charge pump, the chuck actuator, the tailstock quill, and (on lathes with a subspindle) the balancing cylinder. When the pressure transducer drops below the configured threshold, the controller trips the E-Stop chain and stops the spindle. Typical root causes are:

• Charge pump relief valve set too low for the warm-up viscosity of the hydraulic oil.
• Hydraulic oil temperature high (cold-start viscosity drop is rare; warm-oil thinning is common after a long cycle).
• Filter blocked, starving the chuck and tailstock actuators at higher demand.
• Pressure switch chattering under flow-induced droop, causing the OK signal to drop momentarily.
• Spindle-monitoring debounce time set too short in the PLC to ride out the warm-up ramp.

To diagnose, monitor the pressure-switch contact and the corresponding PLC input (typically a digital input on the 802D sl PLC, accessed via the ladder view). The input is wired NC or NO depending on the builder, but in both cases the input must remain stable while the spindle ramps to the programmed RPM. If the input is mechanically sound, increase the debounce in the PLC logic or add a small filter so the OK signal survives the warm-up ramp.

Hydraulic Pressure Interlock Chain on the 802D sl

The 802D sl ladder program reads the hydraulic OK signal on a fast input and routes it through the spindle enable chain. The chain typically follows this pattern in the 802D sl subprogram library:

[Spindle enable from NCK] AND [Hydraulic OK] AND [No E-Stop] AND [Lubrication OK] -> [Spindle run]
[Spindle run] AND [Speed reached] -> [Spindle ready]
[NOT Hydraulic OK] OR [E-Stop] -> [Spindle ramp-down] + [E-Stop alarm 600605 or builder-specific]

The interlock is implemented in the PLC subprogram provided by the machine builder. The HMI displays the active alarm with the source text Hydraulic pressure low and a numeric alarm ID that depends on the builder's compile. The alarm remains latched until the OK signal is restored and the operator acknowledges with the Cancel or Reset softkey.

Data Backup and Commissioning Archive

Whenever a write-access setting, machine data value, or PLC parameter is changed on the 802D sl, generate a commissioning archive. The procedure is:

1. Insert a FAT32-formatted USB stick or CF card into the operator panel.
2. Press MENU SELECT → Setup → Commissioning → Series commissioning → Create archive.
3. Accept the default file name (or assign a name with the machine serial and the date of the change).
4. Press the OK softkey. The HMI writes a binary archive containing the NCK machine data, the PLC program, the drive data, the compensation tables, and the HMI configuration.
5. Remove the storage medium and label it with the machine serial, the date, and a brief description of the changes recorded.

To restore the archive, navigate to Setup → Commissioning → Series commissioning → Read in archive and follow the prompts. The restore action overwrites the active configuration and requires an NCK reset.

Frequently Asked Questions