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Troubleshooting SIMATIC powerrate Load Management (PRE_LMGM) User Archive Communication Errors in WinCC

Troubleshooting SIMATIC powerrate Load Management (PRE_LMGM) User Archive Communication Errors in WinCC

In SIMATIC PCS 7 energy management architectures running SIMATIC powerrate (e.g., v4.0 SP1 or SP3), when the Load Management faceplate (PRE_LMGM) displays 'Transfer Active! Please Wait' followed by alarm 'Monitoring error archiving' and sets block output QMONERR_S = 1, the failure is caused by an architectural mismatch or timeout between the PLC communication blocks (PRE_UA_S / PRE_UA_R) and the WinCC User Archives. This error occurs when the User Archive structure in WinCC Explorer does not match the archive IDs (Arch_ID and ID parameters) configured in CFC, when outdated WinCC faceplates (@PG_PRE_LMGM.pdl) are mixed with newer AS library blocks, or when the WinCC User Archive service is unstarted.

Table of Contents

SIMATIC Powerrate Load Management Architecture (PRE_LMGM and User Archives)

SIMATIC powerrate is Siemens' standardized energy management add-on for SIMATIC PCS 7 and WinCC, designed to monitor energy consumption, perform peak demand shaving, and execute automated load shedding.

The Load Management function utilizes a multi-tiered data exchange pipeline:
- PRE_LMGM (FB1065): The central load management controller in the S7-400 CPU that monitors active power against agreed utility contract limits and calculates shedding/restoration sequences.
- PRE_UA_S (FB1063) & PRE_UA_R (FB1064): Interface blocks that execute raw data read/write handshakes between the S7 controller and WinCC User Archives.
- WinCC User Archives: Stores load parameters, priority rankings, shedding times, and historical energy profiles in structured SQL tables.
- WinCC Faceplates (@PG_PRE_LMGM.pdl): Provide operator interaction, allowing energy managers to view and adjust load priorities directly from the runtime HMI.

Root Causes of 'Monitoring Error Archiving' (QMONERR_S = 1)

When the faceplate initiates a transfer and fails with QMONERR_S = 1 ('Monitoring error archiving'):

  1. Parameter ID and Arch_ID Misalignment:
    - The Arch_ID parameter defines which specific User Archive table in WinCC is targeted.
    - The ID parameter defines the specific record index within that archive.
    - If Arch_ID in CFC does not match the exact numeric ID of the User Archive generated in WinCC Explorer, the WinCC archive server rejects the read/write request.
  2. Library Version Disparity (SP1 Blocks with SP3 Faceplates):
    - In powerrate v4.0 SP1, archive tags and faceplates utilized legacy communication scripts.
    - In powerrate v4.0 SP3, Siemens restructured internal archive structures to resolve trend locking bugs in PRE_SUM (FB1061). Mixing SP1 AS blocks with SP3 WinCC graphics files (@PG_PRE_*.pdl) triggers communication timeouts.
  3. User Archive Runtime Service Not Running:
    - If the User Archives option is not activated in WinCC computer startup properties, the communication handshake tags remain unserviced.

Configuring Arch_ID and ID Parameters on PRE_LMGM and PRE_UA Blocks

To establish valid communication paths between CFC and WinCC User Archives:

  • Arch_ID Parameter: Must be set to the integer index of the corresponding User Archive defined in WinCC User Archives editor (e.g., Arch_ID := 1 for Load Management Configuration).
  • ID Parameter: Represents the unique feeder or load channel index (e.g., ID := 1 for Feeder 1, ID := 2 for Feeder 2).
  • Ensure that the instance of PRE_UA_S (Send) and PRE_UA_R (Receive) connected to PRE_LMGM share identical Arch_ID values.
  • In WinCC User Archives editor, verify that the archive contains the exact column definitions required by powerrate (Field names: ID, Name, Priority, Power, MinShedTime, MaxShedTime).

Resolving Faceplate and Block Version Inconsistencies (SP1 vs SP3)

When upgrading or deploying powerrate:
1. Uniform Update: Never extract blocks from an SP1 demo project into a PCS 7 system running powerrate v4.0 SP3.
2. Update Master Data Library:
- In SIMATIC Manager, open the Master Data Library.
- Copy the latest blocks (PRE_LMGM, PRE_SUM, PRE_UA_S, PRE_UA_R) from the powerrate v4.0 SP3 system library into the MDL.
- Execute Options > Charts > Update Block Types across all AS programs.
3. Update WinCC Graphics:
- Copy the latest @PG_PRE_*.pdl pictures from the powerrate installation folder into the OS project GraCS directory.
- Run OS compilation to synchronize tags.

Diagnostic Matrix for SIMATIC Powerrate Communication Faults

The table below outlines common powerrate diagnostic error bits:

Parameter FlagMeaningUnderlying CauseCorrective ActionQMONERR_S = 1Send Monitoring ErrorUser Archive failed to acknowledge send job within timeoutVerify Arch_ID; check WinCC User Archive serviceQMONERR_R = 1Receive Monitoring ErrorUser Archive failed to supply requested dataVerify ID record exists in WinCC User Archive tableQERR_CFG = 1Configuration ErrorDuplicate priority numbers or negative load valuesInspect load parameters in WinCC User Archive tableQPARERR = 1Parameter Assignment ErrorInvalid communication DB numbers connectedVerify CFC interconnections to PRE_UA blocks

Step-by-Step Configuration and Recovery Procedure

Follow this procedure to resolve the communication failure:

Step 1: Verify WinCC User Archive Startup

  1. Open the WinCC project in WinCC Explorer.
  2. Open Computer Properties > Startup tab.
  3. Verify that User Archives is checked in the list of active runtime applications.

Step 2: Validate User Archive Table Structure

  1. In WinCC Explorer, open the User Archives editor.
  2. Ensure the powerrate archives are created (e.g., PR_LM_LOADS, PR_LM_CONFIG).
  3. Check the Archive ID number; record the exact integer value (e.g., Archive ID = 10).

Step 3: Align CFC Block Parameters

  1. Open the CFC chart containing PRE_LMGM and PRE_UA_S / PRE_UA_R.
  2. Set parameter Arch_ID to match the User Archive ID from Step 2.
  3. Ensure the handshake trigger tags (bJob, bDone, bError) are cleanly interconnected between PRE_LMGM and the PRE_UA blocks.
  4. Compile and download changes to the AS controller in RUN mode.

Step 4: Test Faceplate Transfer

  1. Open WinCC Runtime; navigate to the Load Management screen.
  2. Open the PRE_LMGM faceplate and click Load from PLC.
  3. Confirm that the status message transitions to 'Transfer Successful' and QMONERR_S remains 0.

Verification

To confirm that powerrate load management is functioning:
1. Faceplate Transfer Audit: Execute both 'Load from PLC' and 'Write to PLC' from the PRE_LMGM faceplate; confirm that data exchanges complete within 2 seconds without monitoring alarms.
2. User Archive Data Parity: Inspect the User Archive table in WinCC runtime; confirm that load shedding priorities match the live values displayed on the operator faceplate.
3. Simulated Load Shedding: Simulate a power surge exceeding the contract peak threshold; confirm that PRE_LMGM sheds secondary loads in accordance with configured priorities.

Limitations and Operational Precautions

Engineering teams must observe the following precautions:
- Modifying User Archive table schemas while WinCC runtime is active can corrupt historical energy logs; perform archive structure modifications during cold maintenance.
- SIMATIC powerrate requires valid commercial runtime licenses for WinCC User Archives and the powerrate package; ensure licenses are installed via ALM.
- Always validate final license quantities and MLFBs against the applicable Siemens catalog and authorized distributor quotation when procuring SIMATIC powerrate add-on packages.

Engineer FAQ

Where can I find the archive error logs in WinCC?

WinCC User Archive transaction errors are recorded in C:\Program Files (x86)\Siemens\WinCC\diagnose\UA_Trace.log.

Can SIMATIC powerrate operate without User Archives?

No. The advanced load management, 15-minute peak forecasting, and historical cost center accounting functions strictly require WinCC User Archives.

Does powerrate support both S7-400 and S7-300 controllers?

Yes. SIMATIC powerrate provides block libraries for both S7-300 (standard STEP 7) and S7-400 / CPU 410 (PCS 7 APL style).

Technical References

Related Articles

Related Tags

  • SIMATIC Powerrate
  • PRE_LMGM
  • User Archives
  • Load Management
  • Energy Automation
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