Configuring and Displaying Prepared Control Strategies on SFC Faceplates in PCS 7

Configuring and Displaying Prepared Control Strategies on SFC Faceplates in PCS 7

To display and configure the Prepared Control Strategy (Prepared CS) on a SIMATIC PCS 7 SFC faceplate in WinCC Runtime, ensure that the SFC Type has multiple Control Strategies defined in its Characteristics, and that the faceplate is operating in 'Manual' mode with the operator authorization Level 5 or Level 6 enabled. In the SFC faceplate, the 'Prepared CS' drop-down allows the operator to select the target strategy for the subsequent start command, modifying the internal 'CS_LL' or 'QCSP' parameter while the currently active running strategy ('QCS') remains undisturbed.

Table of Contents

• Executive Summary
• Architecture and Fundamental Mechanics
• Step-by-Step Implementation Procedure
• Verification
• Limitations and Operational Precautions
• Engineer FAQ
• Technical References
• Related Articles
• Related Tags

Executive Summary

In procedural automation, operators need to prepare the next operational phase (e.g., preparing 'CIP Rinse' while 'Product Transfer' is currently running) so that transitions occur without plant delay. In SIMATIC PCS 7 SFC Types, the faceplate provides dedicated controls for both the active strategy (CS) and the prepared strategy (CS_LL / QCSP). However, operators frequently find the prepared strategy drop-down grayed out, failing to update, or conflicting with automatic recipe controls. This article explains the interaction between active and prepared control strategies on WinCC SFC faceplates and how to configure them properly.

Architecture and Fundamental Mechanics

SFC Faceplate Control Strategy Architecture:

• Distinction Between Active and Prepared Strategy:
• Active Control Strategy (CS / QCS): The strategy currently governing active sequencer steps and actuator outputs.
• Prepared Control Strategy (CS_LL / QCSP): The strategy selected to take effect on the next Start or automatic strategy handover.
• Faceplate Operational Modes:
• Manual Mode (MAN): The operator interacts directly with the faceplate drop-down menus. Changing the Prepared Strategy writes to CS_OP.
• Automatic Mode (AUTO): External CFC logic or SIMATIC BATCH dictates strategies via CS_LI / CS_LL. The faceplate drop-down is locked/read-only.
• Strategy Changing During Run:
• If the SFC Type property 'Allow control strategy change during run' is enabled, the operator can modify the Prepared Strategy while the unit is in Run. Upon clicking 'Apply' or when the active sequence completes, the SFC executes the transition into the prepared sequencer.

Step-by-Step Implementation Procedure

Configuring Prepared Strategy Controls in SFC Types and WinCC:

1. Enable Multiple Strategies in SFC Type:
   - Open the SFC Type in the SFC Editor.
   - In Characteristics -> Control Strategies, configure at least two strategies (e.g., 1 = Agitate_Slow, 2 = Agitate_Fast).
2. Configure Strategy Change Permissions:
   - Open SFC Type Properties -> Options tab.
   - Check Change control strategy during run (if mid-sequence changes are required).
3. Compile and Download to AS and OS:
   - Compile CFC/SFC and download changes to the AS.
   - Compile OS to update WinCC faceplate tag connections.
4. Operating the Prepared Strategy in WinCC Runtime:
   - Open the SFC faceplate in WinCC.
   - Switch mode to Manual.
   - In the 'Prepared Control Strategy' drop-down, select the desired strategy.
   - Click the green checkmark or 'Apply' button to lock in the prepared value.
   - Issue the 'Start' command or allow the active sequencer to finish.

Verification

To verify prepared strategy operation:
1. In WinCC Runtime, open the SFC faceplate; verify both 'Current Strategy' and 'Prepared Strategy' fields are visible.
2. While Strategy 1 is running, select Strategy 2 in the Prepared drop-down; confirm QCSP updates to 2 in CFC test mode.
3. When the active sequence completes, confirm that the SFC switches to Strategy 2 (QCS = 2) seamlessly.

Limitations and Operational Precautions

Operational precautions:
- If the SFC Type is integrated into SIMATIC BATCH, manual selection of prepared strategies from the faceplate is prohibited; Batch recipes control strategy selection exclusively.
- Changing control strategies while steps are actively driving physical equipment can cause abrupt setpoint steps; ensure step transitions evaluate safety interlocks.
- If 'Change control strategy during run' is disabled, the prepared strategy can only be applied when the SFC is in 'Ready to start'.

Engineer FAQ

Why is the Prepared Strategy drop-down grayed out on the faceplate?

The SFC is in Automatic mode, only one strategy is defined in the SFC Type, or the user lacks Level 5 authorization.

What is the difference between CS and QCSP?

CS represents the currently executing strategy; QCSP represents the prepared strategy waiting for execution.

Can an operator change the prepared strategy while the sequence is running?

Yes, if 'Change control strategy during run' is enabled in the SFC Type properties.

Can SIMATIC BATCH pre-select strategies in advance?

Yes, Batch recipe phases allocate and parameterize the target strategy automatically.

Where are control strategy text labels defined?

In the SFC Type Characteristics editor under 'Control Strategies'.

Technical References

• SIMATIC Process Control System PCS 7 SFC for SIMATIC S7
• SIMATIC Process Control System PCS 7 Advanced Process Library (APL)
• WinCC V7.5 / PCS 7 OS Configuration Manual

Related Articles

• Automating Control Strategy Transitions in SIMATIC PCS 7 SFC Sequences
• Automatically Chaining Sequencers and Control Strategies in PCS 7 SFC Types
• Designing and Operating SIMATIC PCS 7 SFC Types Without Control Strategies

Related Tags

• SFC Faceplate
• Control Strategy
• Prepared CS
• QCSP
• WinCC Runtime