C135 PCS 7 (PCS7)
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6 Cielo Ciencia y Tecnología
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Displaying Custom Descriptive Text for Interlock Conditions in PCS 7 APL Faceplates

Displaying Custom Descriptive Text for Interlock Conditions in PCS 7 APL Faceplates

To display descriptive text strings (such as 'Motor Overload Trip' or 'Emergency Stop Active') instead of raw binary numbers (1 or 0) on Advanced Process Library (APL) interlock faceplates in SIMATIC PCS 7 V8.1, configure the text attributes on the associated interlock block (Intlk02, Intlk04, or Intlk08). In the CFC editor, open the object properties of the interlock block, navigate to the specific input pin (In01, In02, etc.), and enter the descriptive text into the 'Text 0' or 'Identifier' property field. After compiling the OS with 'Tags and messages', the WinCC faceplate for the technological block (e.g. MotL) automatically queries and renders these text descriptions.

Table of Contents

Executive Summary

In industrial process automation, operator efficiency during plant upset conditions depends heavily on the clarity of Human-Machine Interface (HMI) diagnostic displays. When operators inspect motor or valve faceplates in the SIMATIC PCS 7 Advanced Process Library (APL)—such as MotL or VlvL—clicking on the interlock status buttons (Permit, Protect, or Interlock) opens the dedicated interlock faceplate view. By default, unparameterized interlock blocks display generic input tags and raw binary digits (In01: 0, In02: 1), forcing operators to cross-reference electrical schematics to identify what tripped the equipment. APL includes built-in metadata mechanisms that render plain-language diagnostic texts (such as 'Lube Oil Pressure Low' or 'Vibration High') directly in the faceplate. This guide details how to parameterize these text attributes in CFC and propagate them to WinCC.

APL Interlock Architecture: Permit, Protect, and Intlock Mechanics

Technological blocks in APL evaluate three standardized interlock channels:

  • Permit (Permit): Starting interlock. If Permit = 0, the motor cannot be started; however, if the motor is already running, a loss of Permit does not shut down the drive.
  • Interlock without Protection (Intlock): Operating interlock. If Intlock = 0, the motor cannot start, and if running, it stops immediately. Reset is typically automatic once permissive conditions return.
  • Protection Interlock (Protect): Safety and equipment protection interlock. Forces immediate shutdown and requires an explicit operator or manual reset handshake (RstOp or faceplate reset) once cleared.

Configuring Input Text Attributes in CFC Interlock Blocks

The interlock logic feeding into MotL is realized via dedicated interlock blocks:

  • Intlk02 (FB1824 - 2 inputs)
  • Intlk04 (FB1825 - 4 inputs)
  • Intlk08 (FB1826 - 8 inputs)

Each input pin (In01 through In08) possesses system attributes:

  • Text 0 (S7_string_0): Text string displayed when the input condition evaluates to 0 (Tripped / Inactive).
  • Text 1 (S7_string_1): Text string displayed when the input condition evaluates to 1 (Healthy / Active).
  • Identifier: User-defined label identifying the physical field instrument (e.g. PT-1042).

AS-OS Text Compilation and Faceplate Display Pipeline

When the engineer executes an OS compilation, the AS-OS engineering compiler extracts the text strings assigned to the interlock block inputs and stores them in the WinCC Text Library (TextDistributor). In runtime, the @PG_Intlk04.pdl faceplate reads the dynamic status word and references the Text Library to display the meaningful operational text.

Interlock Parameter and Text Attribute Matrix

The following table compares the parameter attributes and visual display states for APL interlock blocks:

Interlock Input PinSystem AttributeDefault TextExample Configured TextDisplay Condition in FaceplateIn01Text 0 (S7_string_0)Empty / Raw NameElectric Breaker TrippedDisplayed when In01 = 0 (Fault active)In01Text 1 (S7_string_1)Empty / Raw NameElectric Breaker ClosedDisplayed when In01 = 1 (Healthy)In02Text 0 (S7_string_0)Empty / Raw NameLube Oil Low Pressure TripDisplayed when In02 = 0 (Fault active)In02IdentifierIn02PSL-401Displays instrument tag in faceplate columnIn03Text 0 (S7_string_0)Empty / Raw NameEmergency Stop Button PressedDisplayed when In03 = 0 (Trip active)In04Text 0 (S7_string_0)Empty / Raw NameHigh Bearing TemperatureDisplayed when In04 = 0 (Trip active)

Step-by-Step Configuration Procedure in CFC and WinCC

Method 1: Entering Interlock Text Attributes in CFC

  1. In SIMATIC Manager, open the CFC chart containing the Intlk02 / Intlk04 / Intlk08 block.
  2. Double-click the interlock block to open the Block Properties window.
  3. In the properties window, select the Inputs/Outputs tab.
  4. Locate the input pin to be customized (e.g. In01).
  5. In the Text 0 column, type the trip description: Electric Breaker Tripped.
  6. In the Text 1 column, type the healthy description: Electric Breaker Closed.
  7. In the Identifier column, enter the field tag: Q1-SW.
  8. Click OK to save properties.

Method 2: Compiling OS and Verifying Faceplate Text

  1. In SIMATIC Manager, select the OS object under your PC Station.
  2. Right-click and choose Compile.
  3. Select Changes Only (or Entire OS) and check Tags and messages.
  4. Complete the OS compilation.
  5. In WinCC Runtime, open the faceplate for MotL.
  6. Click the Interlock button; confirm that plain-language text strings render in the interlock window.

Verification

To verify that interlock texts render accurately in runtime:

  1. Normal State Check: In WinCC Runtime, open the motor faceplate. Confirm that healthy interlocks display green checkmarks with the configured 'Healthy' text.
  2. Fault State Simulation: Force In01 = 0 on the interlock block. Confirm that the motor stops, the faceplate button turns blue or yellow, and opening the interlock view displays Electric Breaker Tripped: Active.
  3. Multi-Language Check: If configuring multilingual plants, switch the WinCC runtime language to German or Spanish. Confirm that translated strings display correctly from the Text Library.

Limitations and Operational Precautions

  • String Length Constraints: Interlock text strings are limited to 32 characters in classic APL faceplates; keep descriptions concise to prevent text truncation.
  • OS Compilation Required: Modifying text attributes in CFC requires an OS compilation to transfer strings into the WinCC Text Library; changes will not appear immediately in runtime until the OS is compiled.
  • Bypass Interlock Consideration: If an operator bypasses an interlock via the faceplate (Bypass = 1), the faceplate displays a bypass symbol, but the underlying text remains visible.

Engineer FAQ

Why does the interlock faceplate show numbers instead of my configured text?

This occurs when the OS was not compiled after editing text attributes in CFC, or when text was entered into the wrong attribute column (e.g. Comment instead of Text 0).

Can I configure interlock text directly in WinCC Graphic Designer?

No. APL faceplates are standardized system pictures (@PG_Intlk04.pdl); text is queried dynamically from the AS and Text Library, not hardcoded into pictures.

What is the difference between Text 0 and Text 1?

Text 0 is rendered when the input evaluates to 0 (logical FALSE, typically the tripped fault state), while Text 1 is rendered when the input is 1 (logical TRUE, healthy permissive state).

Technical References

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  • https://industrialautomation.net/search?query=simatic-pcs7
  • https://industrialautomation.net/search?query=advanced-process-library
  • https://industrialautomation.net/search?query=interlocks
  • https://industrialautomation.net/search?query=faceplates
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