Troubleshooting Siemens 840D Alarm 700134: ASUP Not Loaded

1. Alarm 700134 Overview

Alarm 700134 on the SINUMERIK 840D sl is a user-defined alarm (or message) generated by the integrated PLC, surfaced to the HMI through the NCK/PLC interface. The standard text reported in the field is:

M: ASUP POWERON.SPF / REFERENC.SPF not loaded / unlocked

The leading M: indicates a message (informational) rather than a hard stop alarm. However, because the asynchronous subprograms it references are mandatory during the controller's startup sequence, the message effectively blocks NCK readiness: until the referenced POWERON.SPF or REFERENC.SPF routines are loaded and the corresponding enable signals are set, the machine refuses to leave the power-on state cleanly and downstream operations (reference point approach, program start, M30 reset) remain inhibited.

Three characteristics distinguish this alarm from typical NCK errors:

1. It is PLC-originated, not generated by the NCK interpreter. The 7xxxxx range is reserved for the PLC user program and HMI messages.
2. It is machine-builder authored. The exact wording and the conditions that trigger it are programmed in the machine builder's PLC project (STEP 7 Classic or TIA Portal project that compiles the SINUMERIK PLC 317-2DP/PN).
3. It is interlock-driven. A physical or logical condition (a guard switch, an E-Stop, a hydraulic pressure switch, a chuck state, etc.) prevents the ASUP enable from being granted, and the PLC raises the message to alert the operator.

2. ASUP (Asynchronous Subprogram) Architecture in SINUMERIK 840D

An Asynchronous Subprogram (ASUP) is a subprogram that the NCK starts in a channel independently of the currently active program flow. ASUPs are the mechanism the controller uses to perform mandatory events such as:

• Initialization after Power On (POWERON.SPF)
• Initialization after a Reset (RESET.SPF)
• Initialization after referencing (REFERENC.SPF)
• Initialization on mode change, program end, or specific M-functions

ASUPs are configured using machine data in the _N_ASUP_ directory. The relevant setting data items are summarized below:

The PLC interface for ASUP control uses the NC-Var-Selector signals in the channel DB (DB21..DB30 for the first NC, DB31..DB40 for the second NC):

• DB21..DBX30.0 – ASUP enable from PLC (1 = ASUPs may be processed)
• DB21..DBX30.1 – ASUP enable from operator panel (HMI key)
• DB21..DBX30.2 – ASUP stop requested
• DB21..DBX7.0..7 – ASUP active / interrupted state bits

If the PLC never sets DBX30.0 (or resets it because a guard is open), the NCK will not load the POWERON.SPF or REFERENC.SPF, and the message "not loaded / unlocked" is generated. This is precisely the path that produces alarm 700134.

3. Decoding the Alarm Text

The text "ASUP POWERON.SPF / REFERENC.SPF not loaded / unlocked" contains three diagnostic fragments:

Splitting the text into its two halves — not loaded and unlocked — is the single most important diagnostic step. It tells the engineer whether to look in the file system first, or in the PLC interlock logic first.

4. Root Cause Hierarchy: From User-Level to NCK-Level

Field occurrences of 700134 sort into four descending layers. Always walk the layers top-down, because the cheapest checks (operator panel) precede the most expensive (PLC project rebuild).

The reference incident that produced this article is a textbook L1 case: the conveyor belt guard against chip ejection had triggered (i.e., the guard's safety switch was open), the PLC saw the input fall, denied the ASUP enable, and the HMI displayed the message. Once the operator closed and latched the guard (or, as reported, the toggle switch for the guard was re-energized), the ASUP enable was granted, POWERON.SPF was loaded, and the alarm cleared without an NCK reset.

5. PLC Safety Interlock Investigation (Primary Cause Path)

For L1 / L2 issues, work the PLC inputs in this order. Each row also tells you which HMI diagnostic screen exposes the signal directly.

1. Door and enclosure guards — HMI: Diagnostics > PLC > Inputs/Outputs. Look for I 1.0..I 1.7 (typical guard switch module), E_StopOK tag, DoorClosed[1..n] tags.
2. Chip conveyor interlocks — The exact failure that triggered 700134 in the source incident. Verify the conveyor's chip guard (often called ConveyorGuardClosed, Schutz_Kuehlmittel, or similar) is closed and the safety relay (Sick, Pilz, Schmersal safety relay) is in the K1/K2 state.
3. Hydraulic / pneumatic pressure — Pressure switch HydPressureOK, PneumOK. If pressure is below the threshold, ASUP enable is denied on many builder projects.
4. Spindle / chuck state — SpindleStopped, ChuckClosed, ToolClamped. The PLC often requires the spindle to be stopped and the chuck closed before the ASUP can be loaded safely.
5. Mode key switch — The MCP returns the mode in DB1000..DB1007 (symbolic name MCP1In / MCP2In). For most builders, modes 1 and 0 are allowed; modes 2/3/4 may suspend ASUPs.
6. Drive enable chain — DB31..DBX2.1 (Pulse Enable) and DB31..DBX2.0 (Controller Enable). If drives are not enabled, the PLC may not issue ASUP enable either.

The standard way to confirm that an interlock is the cause is to open the HMI screen Diagnostics > PLC > Status (HMI Advanced / Operate) and inspect the boolean tag that the builder's program uses to drive DB21..DBX30.0. The name varies; the builder's symbol table is the only authoritative source.

6. File System Verification: POWERON.SPF and REFERENC.SPF

If the alarm text explicitly cites "not loaded" and the interlock is closed, the next check is the file system. The two subprograms must exist in the active work offset (commonly _N_CMA_DIR).

Verification procedure on the HMI:

1. Press Menu Select > Commissioning > File System on HMI Operate, or Services > File System on HMI Advanced.
2. Navigate to NC Active > CM.
3. Confirm _N_POWERON_SPF and _N_REFERENC_SPF exist. If they are missing, the ASUP "not loaded" branch is the dominant cause.
4. If the files are present, check the work offset selection. ASUPs are resolved against the work offset whose name is in MD 20150 / $MC_GCODE_RESET_VALUES[0] or the active _N_CH_DIR. A common failure mode is that the builder copies the file into a work offset (e.g. _N_WPD_DIR/_N_WP1_WPD) but the active work offset is different.

7. Machine Data and Setting Parameters

Confirm that the ASUP framework is enabled in the machine data. The following entries must not be set in a way that disables the PowerOn / Referencing ASUPs:

To check from the HMI, go to Diagnostics > MD Display > Search and enter the MD number. Press the Continue search key to confirm the value. If the value deviates from the builder's commissioning sheet, the builder's commissioning engineer must authorize the change before the field engineer edits it. Do not write to MD 20114 in production without a documented builder sign-off.

8. Recovery and Reset Procedure

Once the root cause has been identified, the following sequence restores the controller. The order is important: never power-cycle past a known interlock, because the PLC will simply reissue the message.

1. Resolve the interlock — close the guard, restore pressure, switch the operating mode key to the correct position, or repair the failed input.
2. Acknowledge the message — press the Alarm Cancel (CANCEL) key on the MCP. This clears the HMI-side message display but does not re-trigger the ASUP.
3. Reset the NCK — press the Reset key on the MCP. The NCK performs a controlled reset, which fires RESET.SPF and re-attempts to load POWERON.SPF.
4. If the alarm persists — the reference incident required a combined key press: Reset on the MCP plus Alarm Cancel simultaneously. This dual-reset path is implemented in the builder's PLC to differentiate a "cancel and retry" from a true operator reset. Hold both for 1–2 s.
5. If still persistent — perform an NCK Cold Start only with the builder's authorization: Menu Select > Commissioning > NCK Reset > Cold Start (with default values). This will overwrite any modified setting data back to the machine data defaults, so record the current setting data first.

9. Verification Checklist

After the recovery sequence, run through this checklist to confirm the ASUP is actually loaded and the message is gone for the right reason.

10. Related Alarms and Cross-References

Alarm 700134 frequently travels with a small constellation of related numbers. Recognizing the cluster helps the field engineer identify the layer quickly.

The PLC user alarm range is configured by the machine builder using the SINUMERIK HMI Pro tool, with the project-specific texts bound to DB18 ranges. Reference the builder's alarm list for the exact text-to-cause mapping.

11. Field-Proven Prevention Strategy

Once the immediate incident is resolved, three engineering actions reduce the probability of recurrence. These come from accumulated field experience on 840D retrofits and builder acceptance tests.

1. Add explicit HMI text for 700134 — even if the message is preserved, append a second line in the builder's alarm text such as "Check conveyor guard and close before pressing RESET." The default text "not loaded / unlocked" is a developer's note, not an operator message.
2. Document the mode-key position — most builders ship the machine in mode 1 (set-up) for installation and mode 0 (operator) for production. If the operator panel is in mode 3 (MDI) on first power-up, the ASUP enable is often denied. Add a one-page laminated card to the cabinet door.
3. Verify the file-system layout annually — many POWERON.SPF files are lost when an operator performs an HMI Setup > Series Commissioning on the wrong work offset. Add a quarterly backup step to the maintenance plan that archives the entire _N_CMA_DIR to the SINUMERIK Operate backup CF card or network share.

12. Frequently Asked Questions