Integrating Compact Didactic Process Skids and Package Units into SIMATIC PCS 7

To integrate compact didactic plants or third-party package units (such as Festo multi-tank pumping and reaction rigs originally controlled by S7-300 or S7-1200 PLCs) into a SIMATIC PCS 7 environment, implement the Siemens Package Unit integration architecture via PCS 7 Database Automation (DBA). Rather than forcing non-compliant S7-300 CPUs into native PCS 7 AS chart containers, the package unit controller executes standard STEP 7 logic and exposes structured Data Blocks over Industrial Ethernet. PCS 7 DBA scans the PLC's DB addresses, maps operational variables into standardized Advanced Process Library (APL) technological types, and automatically generates WinCC OS graphics, block icons, and alarms matching the DCS supervisory standard.

Executive Summary

In university laboratories, vocational training centers, and industrial processing pilot plants, compact training skids—such as Festo Didactic multi-reservoir pumping, heating, and chemical reaction rigs—provide hands-on process dynamics. However, academic curricula and plant modernization projects frequently require integrating these standalone skids into a centralized SIMATIC PCS 7 process control architecture. Because small didactic rigs are typically equipped with compact factory automation PLCs (e.g., CPU 315F-2 PN/DP or S7-1500) that cannot function as native PCS 7 Automation Stations, engineers must apply Package Unit integration methodologies. Utilizing PCS 7 DBA enables complete DCS visualization and supervisory control without discarding existing skid automation hardware.

Architecture and Fundamental Mechanics

The Package Unit integration architecture bridges standalone PLC controllers into the PCS 7 DCS environment:

The Role of Package Units in Process Control: In modern industrial facilities, package units (e.g., refrigeration skids, chemical dosing skids, vendor-engineered centrifuges) arrive with pre-programmed OEM PLCs. Forcing an OEM skid to be re-written in PCS 7 CFC often voids manufacturer warranties. Instead, PCS 7 treats the skid as a black-box autonomous subsystem that communicates operational setpoints, interlocks, and alarms to the central DCS.
The PCS 7 DBA Integration Pipeline:
- S7 Communication Interface: The package unit PLC configures structured DBs (e.g., DB_PUMP, DB_REACTOR, DB_PID) containing standard command words, status words, and measurement variables.
- DBA Type Mapping: Inside PCS 7 DBA (Database Automation), the engineer defines or selects standard AS-OS technological types. DBA browses the STEP 7 project or offline symbol table of the S7-300 controller, binding raw DB addresses to structured APL-style types.
- Automated OS Compilation: When DBA compiles, it directly populates the WinCC Tag Management, Alarm Logging, and Plant Hierarchy databases, instantiating standard PCS 7 faceplates and block icons that seamlessly match native S7-400 process displays.
Communication Layers: Communications route across the Industrial Ethernet plant bus or terminal bus using standard S7 Protocol communication (TCP/IP or ISO-on-TCP). WinCC connects via the SIMATIC S7 Protocol Suite -> TCP/IP channel.

Step-by-Step Implementation Procedure

Integrate a compact didactic process skid into PCS 7 using the following engineering procedures:

Structure Data Blocks in the Skid PLC Program:
- In the S7-300 / S7-1200 / S7-1500 project, organize process variables into standardized UDTs (User Defined Types) or structured DBs:
- Pump_1_DB: Command bits (Start, Stop, Auto, Man), Status bits (Running, Fault, Tripped), and Speed setpoints.
- Reactor_PID_DB: Process Variable (Level/Flow), Setpoint, Manipulated Variable, Gain, Integration Time.
- Compile the skid PLC program and assign a static IP address on the plant Ethernet subnet.
Configure S7 Connection in WinCC OS:
- In SIMATIC Manager on the PCS 7 Engineering Station, open the WinCC OS project.
- Open WinCC Explorer -> Tag Management -> SIMATIC S7 Protocol Suite -> TCP/IP.
- Create a new connection named Skid_Festo_AS and configure the IP address, Rack 0, Slot 2 (for S7-300 CPU).
Configure PCS 7 DBA:
- Launch PCS 7 DBA from SIMATIC Manager or the Windows Start menu.
- Create a new DBA project and link it to the WinCC OS database.
- Under Controllers, add Skid_Festo_AS as a generic S7 PLC source.
- Import the symbol table or STEP 7 project file of the didactic skid.
- Map the skid DB structures to APL technological types (e.g., map Pump_1_DB to MotL_DBA, map Reactor_PID_DB to PIDConL_DBA).
- Assign technological tags to the appropriate Plant Hierarchy folders (e.g., Plant/Didactic_Skid/Reactor).
Compile DBA and Generate Graphic Block Icons:
- In DBA, click Compile OS.
- DBA generates WinCC tags, message records, and places block icons into the assigned WinCC process pictures.
- Download the OS project to the WinCC runtime station.

Verification

Verify package unit communication and supervisory control:

Channel Connection Status: Open WinCCChannelDiagnosis.exe. Verify that the connection Skid_Festo_AS under TCP/IP reports State: Connected with incrementing telegram counters.
Faceplate Control Test: Open the WinCC process graphic. Click the pump icon. Send a Start command from the faceplate. Confirm that the physical pump on the didactic rig energizes and feedback indicates Running.
Alarm Reporting Validation: Force a low-level trip condition on the reactor. Confirm that WinCC displays an incoming process alarm with accurate alarm logging.

Limitations and Operational Precautions

Package units integrated via PCS 7 DBA do not support high-precision 1 ms sequence of events (SoE) time stamping, as standard S7-300 CPUs lack hardware time-stamping AS buffers. Furthermore, controller-to-controller interlocks between the S7-300 package unit and native S7-400 DCS controllers must be coordinated over S7 connections (PUT/GET or BSEND/BRCV), which introduces slight network latency compared to native central backplane communication.

Engineer FAQ

Why use PCS 7 DBA instead of manually creating tags in WinCC Tag Management?

PCS 7 DBA automatically builds standardized APL-style faceplate structures, generates alarm logging records, and integrates with the Plant Hierarchy, ensuring external PLCs look and operate identically to native S7-400 blocks.

Can a single WinCC OS supervise multiple third-party package units simultaneously?

Yes. WinCC OS can connect to multiple independent S7-300, S7-1500, and third-party Modbus/OPC controllers concurrently alongside native S7-400 controllers.