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

Resolving CFC Block Version Timestamp Conflicts and PLCSIM Watch List Deactivation in SIMATIC PCS 7

Resolving CFC Block Version Timestamp Conflicts and PLCSIM Watch List Deactivation in SIMATIC PCS 7

When CFC charts fail to simulate because DB timestamps differ between charts and the offline block folder, execute 'Options > Block Types' in the CFC editor, select the mismatched blocks (e.g. VlvL, Pcs7DiIn), and update them to the chart folder version. If PLCSIM then generates the warning 'Cannot add all parameters to watch list. The parameters affected were deactivated', the issue arises because parameter monitoring is suppressed when inputs/outputs are set to invisible or when the watch list dynamic bandwidth limit is exceeded. Enable 'Generate test capability' in CFC compilation settings, ensure target parameters are set to visible in the block interface, and reduce concurrent monitored variables.

Table of Contents

Executive Summary

Simulation using S7-PLCSIM on the Engineering Station is the cornerstone of control logic verification in SIMATIC PCS 7. However, engineers frequently encounter two interconnected obstacles during initial simulation setup: first, compilation or test mode aborts with the message 'the following DBs could not be read back because the time stamps in CFC and in the block folder diff' and no instance DBs are generated for newly inserted technological blocks (such as VlvL or Pcs7DiIn). Second, after updating block versions, attempting to monitor variables in CFC Test Mode triggers the popup: 'Cannot add all parameters to watch list. The parameters affected were deactivated'. Resolving these issues requires synchronizing the chart type pool with the offline block container and configuring dynamic parameter monitoring attributes correctly.

Root Cause 1: Block Interface Timestamp Mismatches in CFC

PCS 7 maintains strict interface consistency. Every Function Block (FB) in the offline block folder has an internal interface timestamp. When an FB is instantiated in CFC:

  • The CFC chart references the block type stored in the chart folder (charts\block types).
  • If blocks in the offline Blocks folder were modified, recompiled, or imported from a different library without updating the CFC chart types, a timestamp discrepancy occurs.
  • The CFC compiler detects this conflict and refuses to generate or compile instance DBs to prevent data corruption.

Root Cause 2: PLCSIM Watch List Parameter Deactivation

In S7-PLCSIM and live AS monitoring, the Watch List enables dynamic tracking of values. Parameters are deactivated by the monitoring subsystem under the following conditions:

  • Invisible Attribute: The parameter has the attribute S7_visible = false or visibility was unchecked in CFC.
  • Test Capability Disabled: The CFC program was compiled without checking 'Generate test capability' in the compilation dialog.
  • Bandwidth / Buffer Limit: Monitoring too many complex structured variables simultaneously exceeds the communication buffer allocation in S7-PLCSIM or the S7-400 CP buffer.

CFC Test Mode Dynamic Monitoring Mechanics

When CFC enters Test Mode (Debug > Test Mode):

  1. The editor registers active watch list items with the controller's cyclic execution engine (OB1 or cyclic interrupt OBs).
  2. If a parameter's dynamic monitoring flag is suppressed, PLCSIM refuses the watch job and returns the parameter deactivation error.
  3. Setting parameters to 'Active for monitoring' inside the watch table restores communication.

Diagnostic and Resolution Matrix

The following table summarizes error symptoms, root causes, and resolutions for CFC simulation faults:

Error SymptomTechnical Root CauseDiagnostic LocationCorrective Engineering ActionDB timestamp diff errorFB interface in block folder != chart folderCFC Compile LogExecute Options > Block Types > New Version in CFC.No DB created for VlvLUnresolved type conflict prevents DB generationCFC Chart compilationUpdate block types from Master Data Library; compile full.Watch list parameters deactivatedParameters marked invisible / not configured for testCFC Watch List dialogEnable parameter visibility and compile with 'Test capability'.PLCSIM CPU STOP on downloadMemory bottleneck or missing system blocksPLCSIM Diagnostic BufferReset PLCSIM instance memory; perform complete download.Slow watch list refresh rateExceeded communication job buffer limitCFC Debug propertiesReduce number of monitored pins; increase cycle time.

Step-by-Step Procedure to Synchronize Blocks and Restore Monitoring

Method 1: Synchronizing Block Types in the CFC Editor

  1. Open any CFC chart in the S7 program.
  2. From the menu bar, select Options > Block Types.
  3. In the Block Types dialog, compare the Block folder offline list (left) with the Chart folder list (right).
  4. Select the affected technological blocks (e.g. VlvL, Pcs7DiIn, MotL).
  5. Click New Version (or transfer via ->).
  6. A confirmation dialog appears detailing required chart updates; click Yes to proceed.
  7. Execute Chart > Compile > Changes Only (or Entire program if structural interfaces changed).
  8. Download changes to S7-PLCSIM.

Method 2: Enabling Test Capability and Parameter Visibility

  1. In the CFC editor, select Chart > Compile > Charts as Program.
  2. Ensure the checkbox Generate test capability is checked before compiling.
  3. Open the chart containing the blocks to be monitored.
  4. Right-click the block icon (e.g. VlvL) and select Object Properties.
  5. In the I/O table, locate the parameters you wish to monitor.
  6. Ensure the Visible checkbox is checked and that Active for monitoring is enabled.
  7. Enter Test Mode (Debug > Test Mode); add the selected pins to the watch window.

Verification

To verify that block synchronization and dynamic monitoring are operational:

  1. Compilation Cleanliness: Compile the charts. Confirm that compilation finishes with 0 errors and instance DBs are successfully created.
  2. Simulation Download: Download the compiled program to S7-PLCSIM without timestamp mismatch prompts.
  3. Watch List Verification: In CFC Test Mode, add valve parameters (PosReal, FbkOpenOut, Status1) to the watch list. Confirm that live values update cyclically without parameter deactivation warnings.

Limitations and Operational Precautions

  • Full Download Risk: Updating block types to a new interface version requires a full compilation and full download, which places an active physical S7-400 CPU into STOP. Perform block type updates during scheduled outages.
  • Memory Consumption: Compiling with 'Generate test capability' increases the size of MC7 machine code in CPU work memory; disable this option for final production commissioning if controller memory is constrained.
  • PLCSIM Limitations: PLCSIM simulates logic execution accurately, but timing-dependent communication diagnostics differ from physical hardware.

Engineer FAQ

Why did my valve block instance DB disappear after editing the library block?

Modifying a block interface invalidates existing instance DBs until 'Options > Block Types' is executed to re-link charts.

Can I monitor blocks in CFC Test Mode without adding them to a watch list?

Yes, by double-clicking individual block pins or hovering over connections while Test Mode is active.

Does updating block types in one chart update all charts in the CPU?

Yes, 'Options > Block Types' updates the type definition globally across all CFC charts within that S7 program.

Technical References

Related Articles

Related Tags

  • https://industrialautomation.net/search?query=simatic-pcs7
  • https://industrialautomation.net/search?query=cfc-editor
  • https://industrialautomation.net/search?query=plcsim
  • https://industrialautomation.net/search?query=troubleshooting
6 respuestas