C135 PCS 7 (PCS7)
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Reassigning Block Contacts in SIMATIC PCS 7 SFC Type Instances

Reassigning Block Contacts in SIMATIC PCS 7 SFC Type Instances

To reassign or reconnect an SFC block contact in a SIMATIC PCS 7 SFC Type instance without manually deleting dozens of individual pin connections, make a copy of the block contact within the SFC Type Characteristics, delete the original contact, and rename the copy to the original name. This severs all invalid external chart interconnections instantly. Then, establish a single connection from the SFC instance to the correct equipment block, automatically resolving all member pins. Alternatively, in modern architectures using Equipment Phase Types (EPHT) and Control Module Types (CMT), simply change the assigned Control Module in the EMT/EPHT assignment table to repoint all interconnections automatically.

Table of Contents

Executive Summary

In batch and sequential process control engineered with SIMATIC PCS 7 SFC Types, Block Contacts provide the primary interface between sequential logic phases and underlying equipment blocks (such as VlvL, MotL, or PIDConL). A common engineering error occurs when an SFC instance contact is accidentally connected to the wrong field device (e.g., connecting to Valve 102 instead of Valve 101). Because a single block contact exposes multiple interconnected inputs and outputs (AutModLi, OpenAut, CloseAut, FbkOpenOut, etc.), manually locating and severing each individual CFC sheet-bar connection is tedious and error-prone. Recreating the contact definition or leveraging modern Control Module Type (CMT) role assignments allows instantaneous, error-free reassignment.

Architecture and Fundamental Mechanics

The architecture of SFC Block Contacts involves multi-pin structural mapping between type definitions and chart instances:

1. The Structure of an SFC Block Contact

Inside the SFC Type editor:
- A Block Contact represents an abstract equipment role (e.g., DISCHARGE_VALVE based on block type VlvL).
- Rather than wiring 10 individual pins manually, the SFC Type bundles all command outputs and feedback inputs into a single logical contact.
- When instantiated on a CFC chart, the SFC block instance exposes all member pins.
- Connecting any exposed pin of the block contact to the corresponding pin on the target valve block causes the CFC compiler to automatically cross-connect all remaining member pins across the sheet bars.

2. The Disconnection Challenge and Type Copy Technique

  • Once established, the multi-pin binding resists partial modification: attempting to wire a single pin to a different valve generates a collision error.
  • Deleting each connection manually requires opening multiple CFC chart sheets.
  • The Re-creation Shortcut: By duplicating the Block Contact definition in the SFC Type Characteristics, deleting the original, and renaming the duplicate back to the original name, all existing sheet-bar connections are wiped out across all instances upon type update. The contact is instantly blank and ready for single-click rebinding.

3. The Modern Solution: EPHT / EMT with CMT Role Assignment

  • In modern PCS 7 architectures (PCS 7 V8.1 onward), sequential control is structured using Equipment Phase Types (EPHT) and Equipment Module Types (EMT) paired with Control Module Types (CMT).
  • In an EMT/EPHT, actuators are assigned as abstract 'Roles'.
  • Reassigning an actuator does not involve touching CFC wiring: the engineer simply opens the EMT/EPHT configuration, changes the assigned CM instance from VLV102 to VLV101, and the system repoints all underlying signals automatically.

Step-by-Step Implementation Procedure

To reassign an SFC block contact using the rapid clearing method:

Method 1: The SFC Type Contact Recreation Technique

  1. In SIMATIC Manager, navigate to the master data library or chart folder and open the SFC Type.
  2. In the SFC Type tree, expand Characteristics -> Block Contacts.
  3. Select the misconnected block contact (e.g., INLET_VALVE).
  4. Right-click and select Copy, then right-click and select Paste (creating INLET_VALVE_1).
  5. Delete the original INLET_VALVE.
  6. Rename INLET_VALVE_1 back to INLET_VALVE.
  7. Save the SFC Type and execute Options -> Block Types in CFC to update all instances.
  8. Open the target CFC chart. Observe that all invalid sheet-bar connections on that contact have vanished.
  9. Click any empty input/output of the clean block contact and drag a connection to the correct equipment block. All member pins interconnect automatically.

Method 2: Process Object View Parameter Clearing (Alternative)

  1. Open SIMATIC Manager and launch Process Object View (Ctrl+4).
  2. Select the Parameters tab and filter by the SFC instance chart name.
  3. Locate the parameter rows corresponding to the misconnected block contact.
  4. Highlight the entries in the Interconnection column and press Delete.
  5. Reconnect to the correct block in CFC.

Method 3: Role Reassignment in EMT / EPHT (Best Practice for CMTs)

  1. In the Plant View, locate the Equipment Module (EMT) or Equipment Phase (EPHT) instance.
  2. Open the Object Properties or Type Configurator.
  3. Under the Role Assignment table, locate the assigned valve.
  4. Click the dropdown menu and select the correct Control Module (CM_VLV101).
  5. Click Apply; all interconnections update automatically.

Verification

To confirm proper block contact reconnection:

  1. CFC Sheet-Bar Verification:
    - Open the CFC chart containing the SFC instance.
    - Inspect the margin sheet bars of the block contact pins; confirm that all references now point exclusively to the correct equipment block.

  2. SFC Instance Test:
    - Switch the SFC instance to Test Mode (Online).
    - Step through the sequence; confirm that the SFC commands the correct valve and reads back its actual limit switches.

Limitations and Operational Precautions

Operational limitations and precautions:

  1. Multi-Instance Impact in Method 1: Recreating the Block Contact in the master SFC Type will sever connections across all instances of that SFC Type in the project. If only one instance is miswired, use Method 2 (Process Object View) or delete connections manually on that chart.
  2. Compile Changes in RUN: Modifying SFC Types may require compiling changes; ensure the plant is in a steady state that permits online delta compilation.
  3. SFC Visualization on OS: Execute an OS compilation if block contact assignments alter plant hierarchy navigation.
  4. Commercial Disclaimer: Verify all software libraries, engineering licenses, and system packages with an authorized Siemens distributor or the Siemens Industry Mall.

Engineer FAQ

What is the fastest way to sever all connections on an SFC block contact?

In the SFC Type, copy the block contact, delete the original, rename the copy back to the original name, and update block types in CFC.

Why does connecting one pin on a block contact wire all other pins automatically?

Block Contacts are pre-engineered interface bundles. When you connect one pin to an APL block, CFC automatically connects all matching command and feedback pins.

What is the difference between an SFC Type block contact and an EMT role?

An SFC block contact wires individual pins at the chart level. An EMT role abstracts the equipment entirely, allowing dynamic drag-and-drop reassignment without touching chart wires.

Can I clear block contact connections using Process Object View?

Yes. In the Parameters tab, locate the SFC instance parameters and delete the contents of the Interconnection column.

Will recreating a block contact in the SFC Type affect other instances?

Yes. If the SFC Type is instantiated multiple times, recreating the contact in the master type will sever that contact's connections across all instances.

Technical References

Related Articles

Related Tags

  • SFC Types
  • Block Contacts
  • CFC Interconnections
  • EMT and EPHT
  • Batch Sequences
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