C135 PCS 7 (PCS7)
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Bulk Mapping and Monitoring Digital Switch Signals in WinCC Without Manual DB Engineering

Bulk Mapping and Monitoring Digital Switch Signals in WinCC Without Manual DB Engineering

To map and monitor hundreds of digital switches (such as flow, level, and pressure switches) in WinCC SCADA without manually creating Data Blocks with S7_m_c attributes, instantiate standard APL digital monitoring blocks MonDiL (FB1847) or small footprint MonDiS (FB1848) in CFC charts. For mass instantiation of hundreds of signals, use the Process Object View (POV) or the Import/Export Assistant (IEA) with Control Module Types (CMT) to auto-generate charts from an Excel schedule. Upon compiling the OS, WinCC automatically creates communication tags, alarm structures, and runtime faceplates without manual variable entry.

Table of Contents

Executive Summary

When engineering large industrial plants containing hundreds of discrete field switches (e.g., high level switches, low pressure switches, flow confirmation contacts), engineers transitioning from classic STEP 7 to PCS 7 often attempt to consolidate all digital bits into a monolithic Data Block, manually flag variables with S7_m_c = true, and wire addresses by hand. This legacy practice contradicts PCS 7 DCS standards, bypasses automated alarm logging, and creates severe maintenance liabilities. This guide demonstrates the certified PCS 7 workflow: leveraging APL monitoring blocks, Process Object View bulk parameterization, and automated OS tag compilation.

Why Manual DB Mapping Violates PCS 7 Design Philosophy

In traditional PLC/SCADA systems, shared Data Blocks are standard practice. However, in SIMATIC PCS 7:

  • Automated Alarm Generation: PCS 7 derives alarms directly from technological blocks using Alarm_8P. Manual DBs lack message definitions and faceplate bindings.
  • Maintenance Overheads: Manually maintaining cross-references between DB bits, CFC charts, and WinCC tags destroys multiproject traceability.
  • DCS Type-Instance Concept: PCS 7 is designed to instantiate standardized Control Module Types (CMTs) or block types (MonDiL), ensuring consistent alarm acknowledgment, filtering, and operational states across all 350 switches.

APL Digital Monitoring Blocks: MonDiL vs MonDiS

Siemens APL provides two specialized blocks for discrete monitoring:

  • MonDiL (Large Digital Monitor, FB1847): Provides comprehensive signal processing: flutter suppression filters (FlutEn), pulse duration stretching, configurable operational messages, maintenance state integration (CSF, MS), and full-featured OS faceplates.
  • MonDiS (Small Digital Monitor, FB1848): Optimized for low memory footprint; provides basic digital state display and message generation without complex flutter filtering, ideal for high-density discrete monitoring.

Bulk Engineering via Process Object View (POV) and CMTs

Manually placing 350 blocks in CFC one by one is unnecessary. PCS 7 provides high-efficiency mass engineering tools:

  1. Control Module Type (CMT): Create a single master template named CMT_Switch containing Pcs7DiIn and MonDiL in the Master Data Library.
  2. Process Object View (POV): Open the Plant Hierarchy in POV, navigate to the Signals tab, and copy/paste tabular rows directly to generate 350 instances in seconds.
  3. Import/Export Assistant (IEA): Export an IEA process object file (*.csv), paste the 350 switch tag names and I/O addresses from the electrical equipment schedule, and re-import to build the charts automatically.

Engineering Architecture Comparison

The following table compares manual DB mapping versus the standard APL modular approach:

| Engineering Dimension | Manual DB Mapping (Legacy STEP 7) | Standard APL Modular Approach (MonDiL/CMT) |
|---|---|---|---|
| Initial Setup Effort | High: Manual variable typing, address mapping | Low: Automated generation via IEA/POV from Excel |
| Alarm Integration | None: Requires manual WinCC bit alarm configuration | Native: Alarm_8P auto-generates timestamped alarms |
| Faceplate Generation | None: Custom graphics must be drawn for 350 switches | Automatic: Generates standardized APL block icons and faceplates |
| Signal Filtering | Requires custom PLC timer rungs per switch | Built-in: Configurable flutter suppression and on/off delays |
| OS Compilation | Fragile: Tag name changes require manual WinCC repairs | Seamless: Dynamic tag resolution via AS-OS compile wizard |
| Process Object Licensing | Zero AS POs consumed | Consumes 1 AS RT PO per instantiated MonDiL block |

Step-by-Step Implementation Procedure

Method 1: Creating a Reusable CMT and Mass Instantiating via POV

  1. In the Master Data Library (BATCH_Lib / Project Library), open Templates.
  2. Insert a new Control Module Type named CMT_DigitalSwitch.
  3. Inside the CMT, place Pcs7DiIn (FB1865) and MonDiL (FB1847). Connect Pcs7DiIn.PV_Out to MonDiL.In.
  4. In the Technological View, assign PV_In as a signal and MonDiL.MsgEvId as a message.
  5. Open SIMATIC Manager and switch to Process Object View (POV).
  6. Under the Plant Hierarchy, select the target process folder and paste 350 instance rows.
  7. In the Signals tab of POV, paste the 350 hardware addresses (I 0.0 to I 43.7) directly from the engineering spreadsheet.

Method 2: AS and OS Compilation

  1. Select the Chart folder and compile the AS program with 'Generate module drivers'.
  2. Download changes to the controller.
  3. Compile the OS using the OS Compile wizard. Confirm that 350 tag structures and alarm messages are created in WinCC.

Verification

To verify bulk digital mapping:

  1. Open WinCC Explorer Tag Management. Confirm that 350 tag structures matching the plant hierarchy (e.g., Plant/Unit/LSH_101) are populated.
  2. In WinCC Graphic Designer, place a picture with generated block icons. Confirm icons reflect the discrete state (Green for normal, Red for tripped).
  3. Toggle a digital input in S7-PLCSIM. Confirm that the WinCC block icon changes color within 1 second and the alarm banner displays the configured switch description.

Limitations and Operational Precautions

  • Process Object Licensing Considerations: Instantiating 350 MonDiL blocks consumes 350 AS Runtime Process Objects (PO). If license capacity is constrained, verify that sufficient AS RT PO licenses are installed in Automation License Manager (ALM) before mass deployment.
  • Process Image Allocation: Ensure the digital input addresses for all 350 switches reside inside the CPU's Process Image Partition assigned to the cyclic interrupt OB.

Engineer FAQ

Can MonDiS be used instead of MonDiL to save controller memory?

Yes, MonDiS consumes significantly less CPU work memory and execution time compared to MonDiL, making it the preferred block when flutter filtering and complex maintenance features are not required.

Does using MonDiS consume fewer Process Objects than MonDiL?

No. In SIMATIC PCS 7, both MonDiL and MonDiS consume exactly 1 AS Runtime Process Object because both blocks generate OS-relevant messages via Alarm_8P.

How can I suppress alarms for 50 inactive switches during plant commissioning?

Set input parameter MsgLock = 1 on the corresponding MonDiL blocks in CFC, or disable the alarm category from the WinCC faceplate using standard operator permissions.

Technical References

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Related Tags

  • https://industrialautomation.net/search?query=simatic-pcs7
  • https://industrialautomation.net/search?query=process-object-view
  • https://industrialautomation.net/search?query=digital-monitoring
  • https://industrialautomation.net/search?query=mass-engineering
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