C135 PCS 7 (PCS7)
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Engineering Best Practices for Implementing SFC Types, EMTs, and EPHTs with CMTs in SIMATIC PCS 7

Engineering Best Practices for Implementing SFC Types, EMTs, and EPHTs with CMTs in SIMATIC PCS 7

In SIMATIC PCS 7 (V9.0 and higher), implement the technological hierarchy by structuring low-level field devices as Control Module Types (CMTs) in the Master Data Library, encapsulating sequential phase logic into SFC Types within Equipment Module Types (EMTs), and orchestrating multi-unit coordination via Equipment Phase Types (EPHTs). Rather than hardcoding direct block interconnections, configure technological commands (such as SetAuto) and statuses (such as IsAuto) using CMT block contacts, and assign technological roles (e.g., 'FillValve', 'Agitator') within the EMT. When instantiating EMTs and CMTs in the Plant Hierarchy, PCS 7 automatically establishes inter-block signal connections based on role assignments, ensuring seamless multiproject synchronization and full compatibility with SIMATIC BATCH and Plant Automation Accelerator (PAA).

Table of Contents

Executive Summary

Sequential control in process automation encompasses diverse operations ranging from simple equipment sequencing (such as automated CIP flush cycles) to multi-vessel batch manufacturing governed by ANSI/ISA-88 standards. Historically, automation engineers created standalone SFC charts (Sequential Function Charts) tied directly to specific chart blocks. While functional for single-use applications, SFC charts cannot be centrally updated or instantiated as standardized types, leading to engineering duplication and severe maintenance overhead across multi-line production facilities.

Beginning in SIMATIC PCS 7 V9.0, Siemens fundamentally modernized sequential engineering by introducing the technological type concept: combining Control Module Types (CMTs), Equipment Module Types (EMTs), and Equipment Phase Types (EPHTs) under the unified framework detailed in PCS 7 Compendium Part C. This role-based architecture decouples sequence phase logic from specific physical tag addresses. This guide outlines the core architecture of SFC Types, EMTs, and EPHTs, provides the verified step-by-step workflow to configure role-based technological commands and statuses, and establishes engineering best practices to maximize code reusability and simplify SIMATIC BATCH integration.

Architecture and Fundamental Mechanics

The technological architecture of PCS 7 V9.0+ establishes a four-tier hierarchical execution model conforming to ISA-88:
1. Control Module Type (CMT):
* Represents individual physical sensors, actuators, and basic control loops (e.g., analog valves, variable speed drives, PID controllers).
* Configured in the Master Data Library (MDL) with standardized Advanced Process Library (APL) blocks (VlvL, MotL, PIDConL).
* Defines Block Contacts: technological interfaces exposing control commands (e.g., SetAuto, ModLiOp) and feedback status bits (e.g., IsAuto, FbkOpenOut).
2. Equipment Module Type (EMT):
* Represents an autonomous functional group of equipment performing a specific technological task (e.g., a dosing manifold, temperature control loop, or pump skid).
* Integrates an SFC Type that defines the state machine, operating states (Ready, Running, Holding, Held, Completing, Completed), step actions, and transition conditions.
* Employs Roles: abstract placeholders for required CMTs (e.g., role InletValve, role RecircPump). In the SFC steps, actions command the role interface (e.g., InletValve.SetAuto = 1) rather than physical I/O pins.
3. Equipment Phase Type (EPHT):
* Operates at the supervisory process cell level, coordinating multiple subordinate EMTs and CMTs to execute complex batch phases (e.g., a multi-step reactor heating and dosing phase).
* Acts as the direct procedural interface to SIMATIC BATCH recipes.
4. Automated Interconnection Engine:
* During instantiation in the Plant Hierarchy (Plant View), the engineer assigns concrete Control Module instances (CMs) to the designated roles in the EMT instance.
* The PCS 7 engineering system automatically generates all cross-chart signal interconnections, eliminating manual pin wiring and preventing connection errors.

Step-by-Step Implementation Procedure

Step 1: Create Control Module Types (CMTs) in the Master Data Library

  1. In SIMATIC Manager, open the Master Data Library of your multiproject.
  2. Navigate to Plant Types > Control Module Types.
  3. Create a new CMT (e.g., CMT_Valve_Analog or CMT_Motor_1Speed).
  4. Open the technological editor and insert the required APL blocks (e.g., VlvAnL and Pcs7AnOu).
  5. Define technological Block Contacts:
    * Under Commands, add SetAuto (mapped to VlvAnL.ModLiOp and VlvAnL.AutModLi = 1) and Open (mapped to VlvAnL.OpenAut = 1).
    * Under Statuses, add IsAuto (mapped to VlvAnL.AutAct.Value) and IsOpen (mapped to VlvAnL.FbkOpenOut.Value).

Step 2: Create the SFC Type and Equipment Module Type (EMT)

  1. In the Master Data Library, navigate to Plant Types > Equipment Module Types and insert a new EMT (e.g., EMT_Dosing_Unit).
  2. Open the EMT in the Technological Editor and insert an SFC Type.
  3. In the SFC Type interface, define the required setpoints, process values, timers, and control strategies (e.g., Strategy 1: 'Fast Dose', Strategy 2: 'Trickle Dose').
  4. Under the EMT Roles folder, insert the required equipment roles:
    * Role 1: DosingValve (associated with type CMT_Valve_Analog).
    * Role 2: FeedPump (associated with type CMT_Motor_1Speed).

Step 3: Program SFC Steps and Transitions Using Role Commands

  1. Open the SFC Type editor to author the sequencer state logic.
  2. In a step action (e.g., Step START_DOSING):
    * Add statement: DosingValve.Open = 1
    * Add statement: FeedPump.Start = 1
  3. In the subsequent transition condition (e.g., Transition FLOW_CONFIRMED):
    * Add condition: DosingValve.IsOpen == 1 AND FeedPump.IsRunning == 1
  4. In the termination step (STOP_DOSING):
    * Add statement: FeedPump.Stop = 1
    * Add statement: DosingValve.Close = 1
  5. Save and compile the SFC Type.

Step 4: Instantiate EMTs and CMTs in the Plant Hierarchy

  1. Switch to the Plant View in SIMATIC Manager.
  2. Navigate to the target hierarchy folder (e.g., Reactor_01 > Additions).
  3. Instantiate the CMTs required for the unit (e.g., creating XV_101 and P_101).
  4. Instantiate the EMT (e.g., EMT_Reactor01_Dose).
  5. In the technological view of the EMT instance, drag and drop the concrete CM instances into their matching roles:
    * Assign XV_101 -> Role DosingValve.
    * Assign P_101 -> Role FeedPump.
  6. Select Options > Synchronize Shared Declarations or compile charts: confirm that all interconnections are automatically generated in the background.

Step 5: Compile and Download to the AS Controller

  1. Execute a complete CFC and SFC compilation (Chart > Compile > Changes only).
  2. Ensure 'Generate module drivers' is selected.
  3. Download changes to the AS controller and verify runtime sequencing.

Verification

  1. In SIMATIC Manager, open the instantiated SFC Type in test mode (Debug > Test Mode).
  2. Switch the SFC instance from 'Manual' to 'Auto' mode.
  3. Command the sequence to 'Start': verify that the SFC transitions smoothly into step START_DOSING.
  4. Open the online CFC chart for valve XV_101: verify that OpenAut transitions to 1 as commanded by the SFC role action.
  5. Simulate feedback: toggle FbkOpenOut = 1 on the valve. Verify that the SFC transition validates and the sequencer advances to the next step.
  6. In WinCC Runtime, open the standard SFC faceplate and confirm that the active step name, elapsed time, and operating state display accurately without script errors.

Limitations and Operational Precautions

  1. Modifying an SFC Type or EMT in the Master Data Library requires synchronizing all instances across the multiproject; test changes in an isolated test project prior to library synchronization.
  2. Changing the interface of an SFC Type (adding/deleting technological I/O parameters) requires an AS program download; verify whether the download can be performed in RUN mode (CiR) or requires a planned CPU stop.
  3. Role-based interconnections rely strictly on block contact names; renaming a block contact in a CMT breaks associated SFC actions until the role assignments are refreshed.
  4. EPHT coordination requires appropriate licensing when linked to SIMATIC BATCH recipes.

Engineer FAQ

What is the key advantage of an SFC Type over a standard SFC chart?

An SFC Type is a centralized, reusable template stored in the Master Data Library. Updating an SFC Type automatically synchronizes all instantiated SFC instances across the entire plant, whereas SFC charts must be updated individually by hand.

What is the difference between an EMT and an EPHT?

An EMT (Equipment Module Type) controls a group of actuators/sensors performing a single functional operation within a unit. An EPHT (Equipment Phase Type) is a higher-level phase that orchestrates multiple EMTs and interfaces directly with SIMATIC BATCH recipes.

How do roles simplify engineering in PCS 7 V9.0?

Roles allow sequence logic to be written against abstract equipment functions (e.g., 'FillValve.Open') rather than hardcoded chart block pins. When creating instances, you simply link a physical valve to the role, and the system automatically wires all connections.

Can I convert existing SFC charts into SFC Types?

While there is no automated 'one-click' converter, you can copy the phase topology and step logic from an SFC chart into a newly created SFC Type in the Master Data Library and bind its actions to CMT block contacts.

Where can I find detailed official guidelines for SFC Types and EMTs?

Siemens publishes comprehensive architectural guidelines and application examples in the PCS 7 Compendium Part C - Equipment Phases with SFC Types (V9.0) (Entry ID: 109780587).

Technical References

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Related Tags

  • SFC Type
  • EMT
  • EPHT
  • CMT
  • ISA-88
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