Configuring and Displaying Step Comments and Operator Prompts in SFC Charts vs SFC Types in WinCC

In SIMATIC PCS 7, displaying step comments and operator prompts on WinCC faceplates differs fundamentally between SFC Types and standalone SFC Charts. SFC Types natively feature dedicated characteristics for operator communication: POSINO (Position Number / Step Note) displays pre-configured informational text for each active step, while OPTIPNO (Operator Prompt Number) generates an interactive prompt requiring operator acknowledgment before step progression. In contrast, standalone SFC Charts do not support POSINO or OPTIPNO characteristics; displaying custom runtime step descriptions with SFC Charts requires writing step text to an OCM-capable STRING helper block in step actions or triggering configured message alarms.

Architectural Divergence Between SFC Types and SFC Charts

In SIMATIC PCS 7, sequential control logic can be built using either reusable SFC Types (defined in the Master Data Library) or individual SFC Charts (created directly within the plant hierarchy).

Operators monitoring sequential batch operations or equipment phases (such as CIP cleaning, chemical dosing, or reactor heating) rely heavily on clear, contextual human-machine interface (HMI) messages:
* Step 10: Filling reactor with solvent...
* Step 20: Heating to 80°C...
* Step 30: Manual confirmation required: Have field sampling valves been closed?

When engineers open the standard SFC faceplate in WinCC (@PG_SFC_Standard.pdl or @PG_SFC_Type.pdl), they often wonder why step comments entered in the engineering editor do not appear automatically in runtime, or how to generate interactive acknowledgment prompts.

The answer depends entirely on whether the sequence was authored as an SFC Type or an SFC Chart.

Operator Communication in SFC Types (POSINO and OPTIPNO)

SFC Types are engineered specifically for standardized ISA-88 batch and unit operations, featuring built-in characteristics for runtime operator interaction:

1. Position Number / Step Note (`POSINO`)

In the SFC Type Characteristics editor, engineers declare a list of text strings under Position texts / Note texts.
Inside the sequential logic, each step is assigned an integer index pointing to one of these strings (POSINO = 1, POSINO = 2).
When the sequencer enters a step, the standard APL faceplate automatically queries the text library and displays the descriptive string (e.g., Wait for Tank to be filled) in the active faceplate banner without custom scripting.

2. Operator Prompt Number (`OPTIPNO`)

Designed for human-in-the-loop validation (e.g., adding manual ingredients or verifying field positions).
In the SFC Type, engineers declare prompt texts under Operator prompts.
A step assigns an integer index to OPTIPNO.
The faceplate immediately displays the prompt text and illuminates an interactive Acknowledge button.
The sequencer transition evaluates whether the operator has clicked the button before advancing to the subsequent step.

Limitations in Standalone SFC Charts

Standalone SFC Charts do not possess the Characteristics tab or the POSINO/OPTIPNO framework. In an SFC Chart, comments typed under Step Properties are static engineering annotations stored in the STEP 7 database; they are not compiled into WinCC runtime tags. Displaying dynamic step text with SFC Charts requires an external data carrier, such as an SCL helper block with an OCM-capable STRING parameter.

Comparison Table - SFC Type vs SFC Chart Operator Text Features

The following table compares operator text, prompt, and alarming capabilities between SFC Types and SFC Charts.

Feature / CapabilityReusable SFC TypeStandalone SFC ChartStep Note Text (POSINO)Natively supported via CharacteristicsUnsupported (Requires custom STRING block)Operator Prompt (OPTIPNO)Natively supported with Faceplate AcknowledgeUnsupported (Requires custom logic & buttons)HMI Faceplate BindingAutomatic via @PG_SFC_Type.pdlRequires @PG_SFC_Standard.pdl or custom PDLOperator Action Alarm LoggingPrompts and acks logged automaticallyRequires manual Event / ALARM_8P blocksMultilingual Text ManagementFully integrated in Text LibraryManual management across chartsTypical ApplicationReactors, batch units, standardized CIP skidsMaster plant startup, utility sequencing

Step-by-Step Implementation of Step Comments and Prompts

Execute the appropriate engineering procedure based on your sequencer architecture:

Method A: Configuring `POSINO` and `OPTIPNO` in an SFC Type

Declare Texts in Characteristics:
* Open the SFC Type in the Master Data Library.
* Open the Characteristics editor.
* Under Note texts, insert text entries:
- Index 1: Filling solvent tank
- Index 2: Heating reactor mixture
- Under Operator prompts, insert prompt entries:
- Index 10: Confirm field sample taken and valve closed?
Assign Values in Sequencer Steps:
* In the SFC Type sequencer view, double-click Step 10.
* In the Actions tab, assign: POSINO := 1.
* Double-click Step 30 (Manual confirmation step).
* In the Actions tab, assign: OPTIPNO := 10.
* In Transition 30, add condition: OPTIPNO = 0 (which signifies operator acknowledgment).
Compile and Download:
* Save and compile the SFC Type.
* Run Options -> Update Block Types in SIMATIC Manager.
* Compile CFC and OS. In WinCC Runtime, the faceplate displays the note texts and prompt acknowledgment button automatically.

Method B: Displaying Step Comments with Standalone SFC Charts

Create an OCM String Block:
* In SCL, create a simple helper block:
scl FUNCTION_BLOCK FB_SfcText VAR_INPUT TextIn {s7_m_c := 'true'} : STRING[32] := 'Idle'; END_VAR BEGIN // Passes string to WinCC END_FUNCTION_BLOCK
Assign Strings in Step Actions:
* In the SFC Chart, place this block or link to it.
* In Step 10 Actions, write: FB_SfcText.TextIn := 'Filling Tank'.
* In Step 20 Actions, write: FB_SfcText.TextIn := 'Agitating'.
Display in WinCC:
* Compile OS. In Graphics Designer, insert an I/O Field or Static Text bound dynamically to FB_SfcText.TextIn.

Verification

Confirm that step notes and prompts operate correctly in WinCC:

Verify Note Text Display:
* Start the sequence.
* Open the SFC faceplate in WinCC Runtime.
* Confirm that the status bar displays Filling solvent tank while Step 10 is active.
Verify Operator Prompt Acknowledgment:
* When the sequencer reaches Step 30, confirm that the prompt text Confirm field sample taken? appears and the OK button becomes active.
* Click OK. Confirm that the button resets, the prompt clears, and the sequencer immediately advances to the next step.
Verify Alarm Journal Audit:
* Open the WinCC Alarm Journal. Confirm that an operator activity message is logged recording the operator user name and prompt acknowledgment timestamp.

Limitations and Operational Precautions

String Length Limits: Keep POSINO and OPTIPNO text strings concise (typically under 32 characters) to prevent text clipping on standard resolution WinCC faceplates.
Transition Logic on Prompts: When using OPTIPNO, ensure the step transition strictly checks for acknowledgment (OPTIPNO = 0); forgetting this condition will allow the sequence to bypass the manual confirmation.
Multilingual Translation: When translating projects into secondary languages, use the Options -> Manage Multilingual Texts utility to translate all SFC Type characteristics.

Engineer FAQ

Can OPTIPNO prompt acknowledgments be logged in WinCC Alarm Logging?

Yes. When an operator acknowledges an OPTIPNO prompt on the SFC Type faceplate, WinCC automatically logs an Operator Action message in the alarm journal detailing user name, station, and timestamp.

Why doesn't the comment in the 'General' tab of an SFC step show in WinCC?

The comment field in the General tab is strictly an internal engineering design note stored in STEP 7. It is not compiled into WinCC runtime tags.

Can I customize the SFC faceplate to show a company logo and custom text?

Yes. By modifying the underlying faceplate PDL files (@PG_SFC_Type.pdl or @PG_SFC_Standard.pdl), you can embed custom graphics, headers, and auxiliary I/O fields.

What is the maximum number of characteristics an SFC Type can hold?

An SFC Type can hold hundreds of setpoints, parameters, block contacts, note texts, and operator prompts, governed primarily by controller data block memory.

Technical References

Related Tags

SFC-Types
SFC-Charts
POSINO
OPTIPNO
Faceplates
Operator-Prompts

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Configuring and Displaying Step Comments and Operator Prompts in SFC Charts vs SFC Types in WinCC