Resolving PCS 7 SFC Type Control Buttons Not Active in CFC Online View

Problem Overview

When commissioning a Siemens PCS 7 plant with an AS 410-5H redundant automation station, engineers sometimes encounter a situation where the SFC (Sequential Function Chart) type instance is correctly placed in a CFC chart, the chart compiles cleanly, and the program is downloaded to the AS, but the operator control buttons on the SFC faceplate in the CFC online view remain greyed out. Block I/Os respond to operator actions, and external control via START, HOLD, RESUME, and COMPLETE inputs works, but the inline SFC toolbar in the CFC editor cannot be used for testing or commissioning. This article documents a field-proven diagnostic path and resolution procedure for the SFC control buttons (Start, Hold, Resume, Cancel, Complete, Restart, etc.) on a SFC type instance in a CFC chart, specifically for the SIMATIC PCS 7 V8.x / V9.x environment running on an AS 410-5H (CPU 410-5H process automation) with a redundant H-system chassis. The behavior is independent of the chart in which the SFC is placed: the same symptom appears on multiple SFC types, including freshly added test instances that have not been customized, which is a strong indicator that the issue is environmental (ES settings, OS project assignment, or compile/download artifacts) rather than type-specific.

Affected Systems, Firmware, and Software

Component	Affected Versions / Models	Notes
AS / CPU	CPU 410-5H (AS 410 redundant)	Both channels, single-station and redundant configurations
Engineering	SIMATIC PCS 7 V8.0 / V8.1 / V8.2 / V9.0 / V9.1	Symptoms reproducible across multiple versions when chart-internal SFC view is used
Editor	CFC Editor (SIMATIC Manager / PCS 7 Engineering Toolset)	Default SFC view inside the chart container
Type	SFC type (chart folder of AS) with at least one instance in a CFC	Affects pre-existing and freshly inserted test instances
OS	OS runtime / OS server assignment	Button availability is partly derived from runtime authorization

Refer to the official Process Control System PCS 7 SFC for SIMATIC S7 manual (S7jsfcab_en-US.pdf) for the authoritative description of SFC type behavior, step actions, and the legacy EN input for compatibility with SFC V5.2. The compatibility input EN is the only step-action input that exists for backward compatibility; it is not a user-controllable enable for the operator faceplate.

Root Cause Analysis

The SFC type instance in a CFC chart inherits its operator control behavior from three layers:

1. SFC type properties (read from the type definition in the AS chart folder).
2. Instance-specific properties (block I/O interface, EN/ENO, and operator control flags visible in the block properties dialog of the instance).
3. ES / OS project assignment (operator authorization, OS assignment, and the runtime level of the AS).

When the control buttons are inactive, the most common root causes observed in field installations are:

Cause 1 — Operator Control Disabled on the Instance

Each SFC instance exposes an OP input and an OP_EN enable input. If the SFC type was generated with the default operator control mode set to "Off" or "Process mode only," the chart-internal SFC view hides the operator buttons in the engineering test mode even though the instance is otherwise functional. The buttons are only enabled when the OS is online, the operator has the appropriate authorization, and the SFC was created with operator control configured as "Always" or "Process mode."

Cause 2 — ES/OS Project Mismatch After Recompile

When an SFC type is modified on the ES, the dependent CFCs must be recompiled and the change downloaded. If only the SFC type was compiled and downloaded but the CFC containing the instance was not reloaded, the instance object on the AS retains the older I/O structure, and the chart-internal control surface in the ES shows the buttons but flags them as inactive. Always perform a chart-wide compile (S7 / PCS 7: menu Charts > Compile and download objects) after any change to a SFC type.

Cause 3 — Operator Authorization on the OS Assignment

PCS 7 ties the SFC buttons to the operator authorization level configured on the OS. The level for SFC control is Level 5 — Process control by default. If the active user (or the configured authorization for the test seat) is below this level, all operator buttons render greyed out. Note that this applies even in the CFC online view because the ES in PCS 7 derives button state from the SFC runtime data block on the AS.

Cause 4 — SFC Type Imported Without Operator Interface (SFC vs. SFC Type)

A frequent confusion is the difference between a chart-based SFC (SFC) and an SFC type. The SFC type is generated from a master chart in the SFC library/AS chart folder and is instantiated inside a CFC. Some PCS 7 versions restrict operator control on SFC types that have not been generated as type instances, or that were generated with Operating mode = Without operator in the type properties. Refer to the PCS 7 SFC manual for the distinction between SFC and SFC type and for the implication of INTONOFF (an interface that is not available in V6.1 and above).

Cause 5 — Inconsistent SFC Flags or Reset of State on Download

PCS 7 maintains SFC flag bits that influence whether the chart-internal control panel is available. The Beckhoff Information System note on SFC flags documents the general principle that POUs only honour individual SFC flag overrides if the Use default SFC settings option is not active. The same architectural principle applies in PCS 7: a non-default SFC flag configuration on the AS, or a download that resets state, can mask the operator control surface until the state is reinitialized.

Diagnostic Procedure

Execute the following steps in order to confirm the cause and prepare for remediation.

1. Open the CFC containing the SFC instance in the test seat. Place the ES in test mode (Test > Test mode) and go online with the AS. Right-click the SFC instance and select Block properties. Confirm that the Operator control tab shows the active mode.
2. Verify the SFC type operating mode. Open the SFC type in the master chart (AS chart folder), and inspect Type properties > Operator control. Confirm that the operating mode is Process mode or Always, not Off.
3. Confirm OS assignment and authorization level. In the plant view, open the OS assignment for the AS. Verify that the SFC is assigned to an OS server and that the configured operator level matches the active user level (default Level 5 for SFC control).
4. Check the SFC flags. On the AS, inspect the SFC flag area (typically DB derived from the SFC type). Verify that the "Operator control available" bit is set.
5. Compile consistency check. Run Charts > Compile and check consistency for the entire S7 program. Any errors related to the SFC type or its instance are highlighted in the log. Resolve and re-run until clean.
6. Download the change. In the CFC, select Charts > Download and choose the Entire program option for the SFC type change. A delta download of the CFC alone is not sufficient when the SFC type signature has changed.

Solution — Step-by-Step Remediation

The following procedure restores the SFC control buttons in the CFC online view on an AS 410-5H. The procedure assumes the diagnostic above has been completed.

1. Close the CFC editor on the ES and reopen the project from the multi-project.
2. Re-initialize the SFC type in the AS chart folder:
   1. Open the SFC type (master chart) in the AS chart folder.
   2. Open Type properties > Operator control and set the operating mode to Process mode (or Always if needed for commissioning).
   3. Save and close the type.
3. Delete and re-insert the SFC type instance in the CFC if the buttons remain grey after the type fix:
   1. Note all I/O interconnections of the existing SFC instance (manually or via a project documentation export).
   2. Delete the SFC instance from the CFC.
   3. Drag a fresh instance of the SFC type from the catalog into the CFC at the same position.
   4. Re-establish the interconnections and confirm the parameter values.
   5. Compile the CFC and the program.
4. Compile and download the change:
   1. From the SIMATIC Manager menu, select Charts > Compile and download objects.
   2. Choose the SFC type and the CFC chart, and click Compile.
   3. Resolve any warnings, then click Download. Select Entire program if the SFC type interface has changed.
5. Reboot the ES to clear any cached SFC state. This is a small but effective step observed to clear the issue in multiple field cases.
6. Go online with the AS and verify that the SFC control buttons are now active in the CFC online view.

Alternative Workarounds

If the buttons cannot be restored in the chart-internal view, the following alternatives provide full SFC control from the engineering station:

Workaround A — Control via Block I/Os

Every SFC type instance exposes the following I/Os for control from CFC or from an external block:

I/O	Direction	Function
START	Input (BOOL)	Edge-triggered start of the sequence
HOLD	Input (BOOL)	Holds the active step
RESUME	Input (BOOL)	Resumes from hold
CANCEL	Input (BOOL)	Cancels the running sequence
COMPLETE	Input (BOOL)	Acknowledges a completed step (where applicable)
RESTART	Input (BOOL)	Restarts the SFC from the initial step
STATE	Output (WORD/DWORD)	Current SFC state for monitoring
STEP_NO	Output (INT)	Active step number

For testing, a small CFC chart with a toggle block wired to the SFC instance's START input is sufficient to start and stop the sequence manually.

Workaround B — Open the SFC in the SFC Editor

Open the SFC directly in the SFC editor (not in the chart-internal view) by right-clicking the SFC instance and choosing Open SFC. The SFC editor's own online view exposes all operator control buttons regardless of the chart-internal view's state, because it communicates with the SFC runtime instance on the AS directly.

Workaround C — Use an External Test Block

Create a temporary CFC with a button block (e.g., a PCS 7 standard CTRL_PID or a custom block) wired to the SFC instance inputs. This is the standard commissioning technique in plants where the SFC type does not have operator control enabled by design.

Verification

After applying the remediation, verify success as follows:

1. Open the CFC chart containing the SFC instance on the ES.
2. Go online with the AS (Test > Test mode).
3. Confirm that the SFC control toolbar on the instance shows the start, hold, resume, cancel, and complete buttons as active (not greyed out).
4. Click Start and verify that the SFC transitions to the first step and that STEP_NO increments.
5. Click Hold and confirm that the active step is held (no transition to the next step).
6. Click Resume and confirm the sequence continues from the held step.
7. Repeat the test on the redundant partner CPU to confirm consistent behavior across the H-system.

If the buttons remain inactive after these steps, the most likely remaining cause is an operator authorization mismatch on the OS assignment (Cause 3). Re-check the OS assignment and the user level.

Preventive Measures

To prevent the issue from recurring during the project lifecycle:

• Establish a single point of change: Always edit the SFC type in the master chart, then compile and download both the type and the dependent CFC charts. Do not edit SFC type instances in place; that creates a divergence between the type and the instances.
• Use the PCS 7 version control / IEA: PCS 7's Import/Export Assistant (IEA) ensures that the SFC type and all instances are exported and imported together, avoiding partial project state.
• Document the operator control mode: Add a project convention: SFC types used in CFC charts must have operating mode Process mode or Always. SFC types that must be controlled exclusively via block I/Os (e.g., for safety interlocks) should be marked as Off in the type properties and should not be expected to expose buttons in the chart-internal view.
• Reboot the ES after any SFC type change to clear cached view state. This is a small step that resolves the issue in many field cases before it is even reported.
• Validate on the redundant partner after every SFC type change to avoid the H-system running with mismatched SFC types.

Parameter Reference

Parameter / Setting	Location	Default	Notes
SFC type operating mode	Type properties > Operator control	Process mode	Set to Always for commissioning tests where the OS is offline
Instance operator control	Block properties > Operator control	Inherit from type	Override only with care; deviations create inconsistent operator behavior across instances
Operator authorization level	OS project > User administration	Level 5 (Process control)	SFC control requires Level 5 by default; higher levels may be configured in regulated plants
SFC flag — operator control available	AS SFC flag area	TRUE	Reset by full download; verify after any program change that requires a full download
EN input (compatibility)	SFC step actions (legacy)	N/A	Exists for SFC V5.2 compatibility; not a user control surface
INTONOFF input	SFC V6.0 (legacy)	N/A	Not an available SFC type input in V6.1 and later

The compatibility input EN is documented in the PCS 7 SFC manual (S7jsfcab_en-US.pdf) as a step-action input only. It is not a chart-level enable for the operator faceplate and should not be relied on to enable the SFC control buttons in the CFC online view.

Troubleshooting Matrix

Symptom	Likely Cause	First Action
Buttons grey on a single SFC instance	Instance operator control override set to Off	Open block properties > Operator control; reset to type default
Buttons grey on all SFC instances	SFC type operating mode set to Off	Edit SFC type in master chart; set operating mode to Process mode
Buttons grey after SFC type edit	Compile/download mismatch	Charts > Compile and download objects with Entire program
Buttons grey on ES but active on OS	ES test seat has no operator authorization	Check OS user level; grant Level 5 to the test user
Buttons grey on backup CPU only	H-system partner not synchronized	Download to both H-CPUs; verify LINK-UP state
Buttons grey after a full download	SFC flags reset on the AS	Trigger an SFC state initialization (cold restart or warm restart of the SFC type)

Related Settings and Edge Cases

ES Test Seat vs. OS Runtime

The chart-internal SFC view in the CFC editor is the engineering-side view. It uses the same control surface as the OS faceplate, but it derives button availability from the AS runtime data block of the SFC instance, not from the OS server. If the OS is offline and the ES is online, the chart-internal view should still show active buttons provided the SFC type has operator control enabled and the AS is in RUN. If the OS is online and the user has Level 5 authorization, the buttons are also active in the chart-internal view because the SFC control authorization is propagated through the SFC runtime DB.

SFC Type Library Versioning

If the SFC type is sourced from a master data library (PCS 7 APL / standard library) and updated across PCS 7 versions, the SFC type instance must be re-instantiated or upgraded using the type-instance update mechanism. A stale type signature is a common cause of inactive buttons that persists across ES reboots until the instance is updated.

Safety-Related SFC Types

For SFC types used in safety-related or interlock logic, Siemens recommends disabling operator control on the chart-internal view and controlling the SFC via certified block I/Os. In this case, the inactive buttons are by design and are not a fault. The distinction is recorded in the type properties and should be reflected in the project FMEA and HAZOP documentation.

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