Selecting Between EMT and EPHT for Continuous and Semi-Batch Processes in PCS 7 V9.1

In SIMATIC PCS 7 V9.1 projects not utilizing SIMATIC BATCH, selecting between an Equipment Module Type (EMT) and an Equipment Phase Type (EPHT) depends on equipment sharing requirements. If multiple distinct process sequences must dynamically command and arbitrate the same lower-level equipment (e.g., two independent sequences sharing a single dosing valve or discharge pump), select EPHT because EPHT natively supports acquiring shared lower-level Equipment Modules. If sequence control is strictly dedicated to a fixed equipment grouping, select EMT. In PCS 7 V9.1, EMT and EPHT are fully interchangeable and can be converted via a single right-click in the Technological I/O Editor.

Executive Summary

When designing continuous or semi-batch automation architectures in SIMATIC PCS 7 V9.1, engineers migrating away from classical Process Tag Types (PTT) are presented with two advanced technological sequence types: Equipment Module Types (EMT) and Equipment Phase Types (EPHT). While both types encapsulate an SFC Type within a CFC chart and utilize Control Module Types (CMTs), confusion frequently arises regarding which construct to deploy—especially in facilities that do not run SIMATIC BATCH.

Although the acronym 'EPH' historically denoted an ISA-88 recipe phase bound to BatchCC, PCS 7 V9.1 decouples this construct for general process engineering. The critical architectural differentiator lies in multi-master control: an EPHT is engineered to dynamically acquire, lock, and command shared lower-level Equipment Modules (EMs), whereas standard EMTs cannot arbitrate shared child modules. This article evaluates the structural capabilities of EMT vs EPHT, outlines library synchronization rules, and explains how to convert between types without re-engineering.

Architecture and Fundamental Mechanics

The technological engineering model in PCS 7 V9.1 structures procedural automation according to modular hierarchy standards:

Equipment Module Type (EMT):
- Represents an autonomous functional group of equipment (e.g., a cooling jacket, an agitator group, or an intake conveyor).
- An EMT controls child Control Module Types (CMTs) directly via role assignments.
- Architectural Constraint: In PCS 7, an EMT assumes dedicated ownership of its assigned CMTs. If another EMT requires access to the same pump or valve, engineering conflicts arise because two EMTs cannot share the same subordinate control module without complex custom interface multiplexing.
Equipment Phase Type (EPHT):
- Represents an operational process phase or procedure (e.g., 'Heat', 'Dose_Additive', 'Transfer', 'Clean_Line').
- An EPHT can command CMTs directly, but critically, it can also acquire lower-level Equipment Modules (EMs).
- Multi-Phase Equipment Sharing: Multiple independent EPHTs (e.g., Phase_Dosing and Phase_Flushing) can reference the same lower-level EM (e.g., EM_Discharge_Pump). When Phase_Dosing starts, it requests and locks EM_Discharge_Pump. Once complete, it releases the EM, enabling Phase_Flushing to acquire it. This arbitration mechanism is native to EPHT even in stand-alone, non-SIMATIC BATCH applications.
Full Interchangeability in PCS 7 V9.1:
- Recognizing that process requirements evolve during detailed engineering, Siemens implemented a direct conversion utility in PCS 7 V9.1: in the Technological I/O Editor, right-clicking an EMT allows selecting 'Convert to EPHT', and vice versa.
Library Synchronization Mechanics:
- SFC Types within an EMT/EPHT must be edited exclusively in the Master Data Library (MDL) Charts folder, updated across projects via 'Options > Charts > Update Block Types...', and technological chart changes propagated via 'Options > Plant Types > Synchronize...'.

Step-by-Step Implementation Procedure

Follow these steps to choose, configure, and synchronize EMT or EPHT objects in PCS 7 V9.1:

Analyze Equipment Sharing Requirements:
- If the sequence operates a self-contained skid with dedicated valves, motors, and instruments: Select Equipment Module Type (EMT).
- If the sequence must share field drives, valves, or auxiliary skids with other operational phases: Select Equipment Phase Type (EPHT).
Create the Type in the Master Data Library (MDL):
- In SIMATIC Manager, open your Master Data Library.
- In the Component View, expand the Charts folder.
- Create the underlying SFC Type defining steps, transitions, and technological actions.
- Create a new template CFC chart in the MDL Plant View and open it in the CFC Editor.
- Instantiate the SFC Type into the chart.
Configure Technological Roles and Type Classification:
- In the CFC Editor, select 'View > Technological I/Os'.
- Right-click the root technological node: select 'Configure as Equipment Phase' (for EPHT) or 'Configure as Equipment Module' (for EMT).
- Define 'Roles' and insert template CMTs (e.g., Role: Feed_Valve, Role: Agitator).
- (If using EPHT): Define lower-level EM roles to enable shared equipment acquisition.
Convert Between EMT and EPHT if Requirements Change:
- If an existing EMT later requires multi-phase equipment sharing:
- Open the EMT in the Technological I/O Editor.
- Right-click the root node and select 'Convert to EPHT'.
- The editor automatically updates the technological schema while preserving all SFC steps, transitions, and block interconnections.
Follow the Standard Master Data Library Synchronization Procedure:
- Always modify SFC Types and template CFCs in the Master Data Library, NEVER directly in project instance charts.
- Step 5A (SFC Block Interface Update): In SIMATIC Manager Component View, select the MDL Charts folder > select the SFC Type FB > select 'Options > Charts > Update Block Types...'. Choose the target project and apply updates.
- Step 5B (Plant Type Synchronization): Select SIMATIC Manager main menu > 'Options > Plant Types > Synchronize...'. The wizard compares the library template against all project instances and synchronizes role assignments, auxiliary blocks, and chart layouts cleanly.
Compile and Download to Controller in RUN:
- Execute an AS program compile ('Changes only').
- Download program changes to the controller in RUN mode.

Verification

In SIMATIC Manager Plant View, verify that the instantiated objects display the correct technological icon (EMT or EPHT).
Open an instantiated EPHT in CFC: verify that role assignments resolve to the specific physical CMTs and shared EMs assigned within that hierarchy folder.
In CFC Test Mode, test the acquisition sequence: confirm that when EPHT 1 activates, it successfully locks the shared equipment, and when it finishes, EPHT 2 can acquire the same equipment without collision.
Confirm that running 'Options > Plant Types > Synchronize' reports: 'All instances are synchronized with the Master Data Library.'

Limitations and Operational Precautions

Converting an EMT to an EPHT in the Master Data Library updates the type definition, but due to known engineering workflow caveats in early V9.1 releases, existing project instances may require manual confirmation or re-synchronization to refresh all technological role links. Operating multi-master shared equipment requires robust interlock programming (Intlk02) to ensure equipment is never commanded simultaneously if arbitration logic fails. Software engineering licenses and library options should be verified through an authorized Siemens distributor or the Siemens Industry Mall.

Engineer FAQ

Do I need SIMATIC BATCH to use EPHT in PCS 7 V9.1?

No. While EPHT originated in batch environments, PCS 7 V9.1 fully supports EPHT in continuous and semi-batch processes without SIMATIC BATCH, providing native equipment sharing and arbitration.

Can two different EMTs control the same lower-level CMT?

No. Standard EMTs do not support sharing the same CMT without custom multiplexing. If multiple sequences must command the same valve or motor, use EPHT with shared lower-level EMs.

Can I easily convert an EPHT to an EMT later?

Yes. In the Technological I/O Editor, right-click the root node and click 'Convert to EMT'. The conversion is bidirectional and preserves logic.

Why must I update SFC block types from the Charts folder rather than Blocks folder?

Updating SFC block types from the Charts folder ensures the compiler evaluates internal sequencer structures and updates instance DB signatures correctly without causing compilation mismatches.

Do EPHT objects consume more AS RT Process Objects than EMTs?

No. Process Object consumption is determined by the underlying technological blocks (the SFC Type FB and driver/motor blocks), not by whether the container is an EMT or an EPHT.