PCS7 Measuring Point Browser: Adding Custom APL Blocks via XML

Overview

The PCS 7 Measuring Point Browser is a WinCC faceplate tool that aggregates the runtime status of process tags (block states, modes, faults, and operator prompts) into a single tabular view. Out of the box, the browser is wired to a fixed set of standard Siemens PCS 7 Advanced Process Library (APL) block types. When a project uses project-specific APL-style blocks (custom faceplates following the 100% APL design rule) or relies on standard APL blocks that are not pre-mapped (for example Intlk2, Intlk8, or interlock composites), the browser will silently skip them.

This article documents the XML-based extension path for the Measuring Point Browser, located in the WinCC Options/SSM directory. The mechanism is the same path Siemens uses internally to ship PCS7_TagStates_APL.xml, and it can be extended with a user-defined XML file that registers additional block types and their status bits.

Prerequisites

How the Measuring Point Browser Resolves Block Types

At OS runtime, the Measuring Point Browser enumerates the configured tag/measured-variable references and, for each one, attempts to read the block type and current status bits. The mapping from block type → displayable column states is driven entirely by XML files in the SSM folder:

• PCS7_TagStates_APL.xml – the shipped Siemens definition covering all standard APL block types.
• PCS7_TagStates_<Name>.xml – any number of additional files following the same schema. The suffix is user-chosen.

Each XML file is loaded in alphabetic order after the shipped APL file, and a block type is matched against the union of all <Types> entries. This is the public extension point and is the only supported way to add custom or supplementary block types.

File Location and Naming

The configuration files reside in the WinCC Options SSM directory:

C:\Program Files (x86)\SIEMENS\WinCC\Options\SSM

Inside that folder you will find:

• PCS7_TagStates_APL.xml – shipped, do not overwrite.
• PCS7_TagStates_<ProjectName>.xml – your custom file. Siemens documents that the suffix after PCS7_TagStates_ is freely selectable; choose a name that reflects the project or the block family (for example PCS7_TagStates_Plant42.xml).

XML Schema – The Two Top-Level Elements

The schema has two top-level child elements. Both must be present even if one of them is empty.

<Columns> – Defining Displayable States

<Columns> defines the available status columns that the browser can render. A column corresponds to a state, not a specific block type. Typical column entries include Manual, Auto, Internal Setpoint, External Setpoint, Operator Prompt, Maintenance, etc.

<Columns>
  <Column Name="Manual"      ID="1"  Icon="@Manual.bmp" />
  <Column Name="Auto"        ID="2"  Icon="@Auto.bmp"   />
  <Column Name="InternalSP"  ID="3"  Icon="@IntSP.bmp"  />
  <Column Name="ExternalSP"  ID="4"  Icon="@ExtSP.bmp"  />
  <Column Name="Operator"    ID="5"  Icon="@OprReq.bmp" />
</Columns>

Each <Column> entry carries:

<Types> – Mapping Block Type to Status Bits

<Types> binds a specific block type (FB type name) to the status bits that drive each column. The browser reads the relevant STATUS_... / MODES_... outputs of the block and lights the column when the bit is TRUE.

<Types>
  <Type FBType="MyCust_Pump" Library="MyLib">
    <Status Column="Manual"     Bit="MODE_MAN"   />
    <Status Column="Auto"       Bit="MODE_AUT"   />
    <Status Column="InternalSP" Bit="SP_INT"     />
    <Status Column="ExternalSP" Bit="SP_EXT"     />
    <Status Column="Operator"   Bit="MSG_REQ_OP" />
  </Type>
</Types>

Key attributes:

Step-by-Step: Adding a Custom APL-Style Block

The procedure below adds a project-specific pump block (MyCust_Pump) to the Measuring Point Browser.

Step 1 – Verify the Block Is 100% APL Style

Open the block in the CFC editor. On the block icon properties confirm:

• APL_Style = TRUE
• Standard status outputs are wired: STATUS_MAN, STATUS_AUT, STATUS_OOS, SP_INT, SP_EXT, MSG_REQ_OP, MSG_ERR, MSG_LOCK.
• Block version is consistent across master data library and project.

Step 2 – Create the Custom XML File

1. Open Notepad (or any XML editor) as Administrator.
2. Create a new file with UTF-8 encoding:

<?xml version="1.0" encoding="utf-8"?>
<!-- PCS7_TagStates_Plant42.xml : project extension for Plant 42 -->
<TagStates>
  <Columns>
    <Column Name="Manual"     ID="101" Icon="@Manual.bmp" />
    <Column Name="Auto"       ID="102" Icon="@Auto.bmp"   />
    <Column Name="OutOfService" ID="103" Icon="@OOS.bmp" />
    <Column Name="Operator"   ID="104" Icon="@OprReq.bmp" />
  </Columns>

  <Types>
    <Type FBType="MyCust_Pump" Library="MyLib">
      <Status Column="Manual"        Bit="STATUS_MAN"  />
      <Status Column="Auto"          Bit="STATUS_AUT"  />
      <Status Column="OutOfService"  Bit="STATUS_OOS"  />
      <Status Column="Operator"      Bit="MSG_REQ_OP"  />
    </Type>
  </Types>
</TagStates>

3. Save the file as PCS7_TagStates_Plant42.xml (UTF-8, no BOM is preferred by WinCC) into:

C:\Program Files (x86)\SIEMENS\WinCC\Options\SSM\

Step 3 – Validate the XML

Open the file in Internet Explorer or Edge (XML view) to ensure it is well-formed. WinCC will not surface parse errors at load time – a malformed file is silently ignored, which is the most common cause of "my custom file doesn't seem to work" reports.

Step 4 – Restart WinCC Explorer and Runtime

Edit the XML in the OS server project as well as in any client project. The Measuring Point Browser loads the SSM files on project activation. After any change you must:

1. Close the WinCC Explorer on the affected station.
2. Close WinCC Runtime (stop the OS project).
3. Reopen WinCC Explorer and re-activate the project.

Step 5 – Verify in the Browser

1. Open a WinCC picture containing the Measuring Point Browser faceplate.
2. Select the user-defined block instance (for example P42/PUMP_001) in the browser tree.
3. Confirm the configured columns light up in line with the live status bits of the AS block.

Step-by-Step: Adding Standard APL Blocks That Are Not Mapped by Default

Standard APL blocks such as Intlk2 / Intlk8 are shipped with the APL library but are not part of the Measuring Point Browser's default mapping. The mechanism is the same as for custom blocks: create a project-level XML that references the FB type and binds it to status bits.

1. Identify the symbolic FB type name (open the block in CFC → right-click → Object properties → Block tab).
2. Confirm which standard status outputs the interlock block exposes (e.g. BYPASS, BYPASSED, MSG_ACK, MSG_ERR).
3. Create PCS7_TagStates_<Suffix>.xml as in the previous section, with a <Type FBType="Intlk2"> entry.
4. Bind each <Status> row to a column that is meaningful for interlock display, e.g. Bypass or Operator Acknowledgement.
5. Restart WinCC Explorer and Runtime on every OS station.

Reference: Common APL Block Types

Troubleshooting Matrix

Field-Proven Best Practices

• One file per project suffix. Use a suffix that names the project or plant (Plant42, UnitA). Avoid generic names such as Custom; they collide when multiple integrators contribute to the same OS.
• Version control the XML. Treat it as source code: store it in the project's revision control with the same discipline as CFC/SFC sources.
• Document the bit mapping. For each <Status> row, add an XML comment naming the block output and its semantic meaning. Future maintenance will depend on it.
• Re-validate after APL upgrades. When the project migrates to a new APL revision, the status output names can change. Re-open each <Type> and verify bit names are still valid.
• Test on a single OS client first. Roll out the XML to one client, exercise the browser, and only then distribute to the rest of the fleet. This makes it trivial to bisect a regression.

Related Configuration Surfaces

The Measuring Point Browser is only one of several status-aggregation tools in PCS 7. Related extension points include:

• Block icon configuration – @PCS7TypicalsAPLLib.pdl and per-project faceplate PDLs in the OS project.
• SFC visualization – chart-based status displays that use their own XML set, located in ...\SFC subfolders.
• Alarm logging – message classes and priorities configured in WinCC Explorer, independent of the SSM XML.

Keeping the SSM XML confined to the status mapping responsibility avoids accidental coupling with faceplate PDLs and message classes.

FAQ