C135 PCS 7 (PCS7)
6C
6 Cielo Ciencia y Tecnología
·Publicada en C135 PCS 7 (PCS7)

Preserving Runtime Process Parameters and Setpoints During Major Version Full AS Downloads in SIMATIC PCS 7

Preserving Runtime Process Parameters and Setpoints During Major Version Full AS Downloads in SIMATIC PCS 7

When performing a mandatory full AS compilation and download with CPU STOP after migrating from SIMATIC PCS 7 V6.1 to V8.1, all active controller data blocks are overwritten with offline initial values, threatening the loss of field-tuned timer values, PID gains, and operational setpoints. To preserve live values without an outdated baseline, use the Process Object View (POV) in SIMATIC Manager to export live parameters: filter the Parameters tab by target block types, copy the live parameter columns directly into Microsoft Excel prior to shutdown, and paste the values back into the offline CFC parameters after migration. Alternatively, execute 'Chart > Read Back' on the running controller immediately prior to performing the full download.

Table of Contents

Executive Summary

Migrating automated facilities across multiple generations of SIMATIC PCS 7 (such as upgrading from V6.1 to V8.1) requires updating system libraries, compiler structures, and communication interfaces. Because technological block interfaces change between major releases, delta downloads are prohibited by the CFC compiler; an initial Full Download (Charts as Program) with the CPU in STOP mode is enforced. However, executing a full download replaces all live data blocks in CPU work memory with the offline project's initial values, destroying months or years of field-tuned operational parameters (custom timer setpoints, PID tuning parameters, batch dosing limits, and totalizer presets). If previous Read Back archives are outdated, automation engineers must capture live values immediately prior to cutover using structured tabular export and restoration techniques.

Why Major Version Upgrades Enforce Full AS Downloads (CPU STOP)

In SIMATIC PCS 7, delta compilation and download in RUN depend on strict binary interface continuity:

  • When upgrading from V6.1 to V8.1, standard library blocks are replaced with newer block versions.
  • Changing a single block interface parameter alters the memory layout and offset offsets of instance data blocks.
  • To prevent pointer corruption and memory collisions, the CFC compiler blocks delta downloads and mandates a full program compile and download with CPU STOP.

The Operational Risk: Overwriting Field Setpoints and Tuning Parameters

In continuous production plants:

  • Operators and commissioning engineers routinely adjust setpoints via WinCC faceplates (e.g. SP_Int, TI, TD, Gain).
  • These adjustments modify the active values residing in the CPU's instance data blocks, but do not automatically feed back into the offline CFC charts on the Engineering Station.
  • Performing a full download pushes the offline initial values into the CPU, resetting critical plant setpoints to default values.

Parameter Read Back vs Process Object View Tabular Synchronization

Two proven engineering workflows safeguard live operational data:

  • Method 1: Live Parameter Read Back (Chart > Read Back): Automatically queries the online CPU via S7 communication and updates all offline CFC block pins marked with S7_m_c = true or S7_read_back = true.
  • Method 2: Process Object View (POV) Excel Export/Import: When dealing with custom, locked, or third-party blocks lacking standard readback attributes, POV displays all block I/Os in a spreadsheet grid. Engineers can mass-copy live values to Excel and paste them back into target inputs after migration.

Parameter Preservation Methods Comparison

The following table compares parameter preservation techniques prior to a major full AS download:

Preservation MethodExecution SpeedScope of CaptureHandling of Custom BlocksRisk ProfileCFC Parameter Read BackAutomated (Minutes)All OCM & readback pinsRequires S7_read_back = trueZero risk; native Siemens tool.Process Object View (POV)Semi-Automated (Excel)Any filtered parameterExcellent for custom blocksRequires strict column sorting verification.Upload Station to PGFastRaw STL blocks (MC7)Captures DB values in STEP 7Prohibited in PCS 7; breaks CFC links.WinCC Tag ExportScriptedWinCC runtime tagsCovers only OCM tagsRequires custom scripting to re-write to AS.

Step-by-Step Procedure to Capture and Restore Live Controller Parameters

Method 1: Executing Full Parameter Read Back Prior to Cutover

  1. Connect the Engineering Station to the running S7-400 AS via the Plant Bus.
  2. Open any CFC chart in the target S7 program.
  3. From the menu bar, select Chart > Read Back....
  4. In the Read Back dialog, select scope: Entire program.
  5. Check both options: Operator control and monitoring (OCM) attributes and Parameters marked for readback.
  6. Click OK. The wizard reads all live values from CPU RAM and commits them into the offline CFC database.
  7. Create an immediate .zip archive of the synchronized project before proceeding with version migration.

Method 2: Tabular Extraction via Process Object View for Custom Blocks

  1. Open Process Object View in SIMATIC Manager (View > Process Object View or F4).
  2. Switch to the Parameters tab.
  3. In the filter bar, filter by your custom block type name (e.g. Timer_Custom).
  4. Sort the table systematically by Chart and Block name.
  5. Highlight the table rows and copy all parameter values (Ctrl + C).
  6. Paste the data into Microsoft Excel and save the spreadsheet as a permanent audit baseline.
  7. After migrating the project to PCS 7 V8.1 and recompiling, re-open Process Object View.
  8. Apply the identical filter and sort order.
  9. Copy the preserved parameter values from Excel and paste them directly into the target input column in POV.
  10. Compile the charts; your live values are now the new offline starting values.

Verification

To verify that critical parameters are preserved after download:

  1. Pre-Download Audit Check: Inspect representative PID controllers and custom timers in CFC. Confirm that offline values match the values documented in the Excel baseline.
  2. Full Download Execution: Execute PLC > Download > Entire Program with the CPU in STOP. Transition CPU to RUN.
  3. Online Monitoring Check: Switch CFC to Test Mode. Inspect critical timer and setpoint outputs. Confirm that field setpoints match pre-cutover operational values.

Limitations and Operational Precautions

  • Sorting Verification in Excel: When pasting data between Excel and Process Object View, ensure row sorting order is 100% identical; mismatched sorting will inject incorrect setpoints into random equipment blocks.
  • Do Not Read Back Over Modified Logic: Never execute Read Back on an offline project that has already undergone structural chart edits; always perform Read Back on the authentic, matching pre-migration backup.
  • Safety Program Values: Fail-safe blocks in S7 F-Systems cannot be updated via standard Read Back; safety parameters must be verified manually against certified safety documentation.

Engineer FAQ

Can Parameter Read Back be performed while the plant is actively running?

Yes, Read Back performs passive read queries from data blocks and has zero impact on controller execution or safety.

Why were some custom timer setpoints not captured by Read Back?

Inputs on custom blocks must have the system attribute S7_m_c = 'true' or S7_read_back = 'true' in their block header to be included.

Can WinCC User Archive be used to store and restore recipe setpoints?

Yes, WinCC User Archives can store operational recipes in SQL Server and re-download them to the PLC via faceplate scripts.

Technical References

Related Articles

Related Tags

  • https://industrialautomation.net/search?query=simatic-pcs7
  • https://industrialautomation.net/search?query=migration
  • https://industrialautomation.net/search?query=cfc-editor
  • https://industrialautomation.net/search?query=process-object-view
6 respuestas