C135 PCS 7 (PCS7)
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Integrating Third-Party Ethernet Equipment (Huber Thermoregulators) into SIMATIC PCS 7 via Open TCP and Modbus TCP

Integrating Third-Party Ethernet Equipment (Huber Thermoregulators) into SIMATIC PCS 7 via Open TCP and Modbus TCP

Integrating third-party Ethernet devices lacking standard PROFINET GSDML files (such as Huber temperature regulators utilizing raw TCP/IP or PB commands) into SIMATIC PCS 7 running on an IPC 627 Box PC is achieved via three standardized architectures. If the device supports Modbus/TCP, engineers should deploy the official Siemens PCS 7 Modbus/TCP Library (Entry ID 75867147), which provides certified blocks (SND_REAL, RCV_REAL, MB_DIAG) and automated alarm integration. If the device uses proprietary ASCII commands over raw TCP sockets, engineers implement Open Industrial Ethernet Communication using TSEND/TRCV blocks in CFC, or connect via an OPC Server gateway on the OS.

Table of Contents

Executive Summary

In specialty chemical, pharmaceutical, and pilot batch plants governed by SIMATIC PCS 7, auxiliary package units—such as Huber thermoregulators, chillers, laboratory balances, and gas analyzers—frequently require integration into the plant automation hierarchy. These specialized instruments often feature standard 10/100 Mbps RJ45 Ethernet ports but lack native PROFINET IO interfaces or vendor-supplied GSDML files. Automation engineers managing systems on industrial PCs (such as the SIMATIC IPC 627 Microbox running PCS 7 V8.0 SP2) must establish robust communication without compromising the real-time execution of the automation controller. This technical article evaluates three proven integration paths: the official PCS 7 Modbus/TCP library, Open TCP/IP communication blocks, and WinCC supervisory gateways.

Communication Architecture for Non-PROFINET Ethernet Devices in PCS 7

Standard PCS 7 field integration expects field devices to function as PROFINET IO Devices or PROFIBUS DP Slaves mapped into HW Config. When a device communicates purely via socket-based TCP/IP:

  • The device cannot be placed directly into the HW Config graphic layout without a certified GSDML file.
  • Bypassing HW Config requires establishing an Application Layer Connection via Open User Communication (OUC), a dedicated fieldbus library, or a supervisory SCADA driver.
  • The controller or IPC acts as a TCP Client/Server, managing socket handshakes, data packet framing, and checksum verification.

Option 1: The Certified Siemens PCS 7 Modbus/TCP Library (Recommended)

If the Huber thermoregulator supports standard Modbus/TCP communication (either natively or via an optional interface card):

  • Certified Library: Siemens provides the official SIMATIC PCS 7 Modbus/TCP Block Library (documented in Siemens Application Example 75867147).
  • Standardized Technological Blocks:
  • SND_BOOL, SND_INT, SND_REAL: Transmit setpoints, start/stop commands, and ramp rates to Modbus holding registers.
  • RCV_BOOL, RCV_INT, RCV_REAL: Read process temperatures, jacket temperatures, pump pressures, and operational states.
  • Job-List: Coordinates sequential read/write polling queues across multiple registers.
  • MB_DIAG: Evaluates connection status and generates native PCS 7 WinCC diagnostic alarms.
  • Advantage: Full integration into PCS 7 alarming, CFC engineering, and OS faceplate standards.

Option 2: Open Industrial Ethernet Communication (TSEND / TRCV in CFC)

If the device communicates exclusively via proprietary ASCII strings (e.g. Huber 'PB' commands like [M01_SP_025.0]):

  • Open Communication Blocks: The AS controller uses standard Open User Communication (OUC) blocks:
  • TCON: Establishes and monitors the TCP/IP socket connection to the device's IP address and port (e.g. Port 5000).
  • TSEND: Transmits ASCII command telegrams.
  • TRCV: Receives incoming ASCII response buffers.
  • TDISCON: Terminates socket sessions during communication faults.
  • String Parsing: Custom CFC logic or an SCL helper function parses the received ASCII string, extracts numeric temperature values, and feeds them into standard APL monitoring blocks (MonAnL).

Option 3: Supervisory-Level Integration via WinCC Direct Channels or OPC

If the thermoregulator is only needed for operator visualization and trending rather than fast closed-loop safety interlocking:

  • Direct SCADA Connection: The device communicates directly with WinCC on the IPC 627 (Box PC) via an industrial Ethernet driver (e.g. Modbus TCP driver in WinCC Tag Management, or a local OPC Server).
  • Controller Offload: This approach completely avoids consuming CPU communication resources on the S7-400 controller.
  • Limitation: Data cannot be used for deterministic controller interlocking unless bridged from WinCC down to the AS.

Step-by-Step Implementation Workflow for Modbus/TCP Integration

To implement the Huber thermoregulator via the PCS 7 Modbus/TCP library:

  1. Procure and Install Modbus Library: Install the PCS 7 Modbus/TCP Library on the Engineering Station.
  2. Configure Connection in NetPro:
    * Open NetPro. Select the AS controller CPU (or CP 443-1).
    * Insert an Unspecified TCP Connection.
    * Configure the partner IP address to match the Huber regulator and set the port to 502 (Modbus standard).
  3. Instantiate Library Blocks in CFC:
    * In a dedicated CFC chart, place the Job-List and MB_DIAG blocks.
    * Place RCV_REAL to read process temperature (Register 40001) and SND_REAL to send temperature setpoint (Register 40002).
  4. Connect to APL Monitoring Blocks: Connect the output of RCV_REAL to an APL MonAnL block to generate alarms and faceplates.
  5. Compile and Download: Compile CFC and OS, and perform a delta download to the AS.

Third-Party Ethernet Device Integration Matrix

The following table compares integration methods for non-PROFINET equipment in PCS 7:

Integration MethodProtocol UsedHardware RequiredImplementation EffortRecommended Use CasePCS 7 Modbus/TCP LibraryModbus TCP (Port 502)Standard CP 443-1 or CPU PNLow (Pre-built blocks & diagnostics)Standard industrial packages with Modbus supportOpen User Comm (TSEND/TRCV)Raw TCP / Proprietary ASCIIStandard CP 443-1 or CPU PNHigh (Custom SCL string parser needed)Devices using proprietary ASCII command setsWinCC Modbus ChannelModbus TCP to SCADAIPC 627 Ethernet portLow (Configured in WinCC Explorer)Supervisory trending; no fast PLC interlockingProtocol Gateway (PN/Modbus)PROFINET IOAnybus / Siemens GatewayModerate (Gateway mapped via GSDML)Real-time I/O integration without PLC library overheadOPC DA / UA ServerOPC ProtocolDedicated OPC server appModerateLegacy instruments with vendor OPC software

Verification

To verify that communication with the Huber regulator is healthy:

  1. Socket Health Check: In CFC, monitor the MB_DIAG or TCON block. Confirm that parameter STATUS = 16#7000 (Connection established) and ERROR = FALSE.
  2. Live Value Polling: Compare the temperature reading on the physical Huber unit front display against the RCV_REAL.Value output in CFC. Confirm values match.
  3. Setpoint Control Test: From the WinCC faceplate, adjust the temperature setpoint. Confirm that the Huber regulator receives and adopts the new setpoint within 1 to 2 seconds.
  4. Communication Failure Simulation: Disconnect the Ethernet cable. Confirm that MB_DIAG asserts a diagnostic alarm in WinCC and sets MonAnL quality code to Bad.

Preventive Network Isolation and Cybersecurity Guidelines

To maintain plant cybersecurity and operational determinism:

  • Isolate Package Units on a Dedicated Subnet: Never connect third-party laboratory equipment directly to the critical Plant Bus or Terminal Bus. Route third-party devices through a secondary CP network interface or industrial firewall.
  • Lock Down Open Sockets: Restrict the controller's TCP communication ports to the exact IP address of the target regulator.

Limitations and Operational Precautions

Raw TCP/IP socket communications do not support deterministic failover or redundant controller synchronization. If an S7-400H pair fails over, open TCP connections must be re-established by the newly active CPU.

When procuring the PCS 7 Modbus/TCP library, communication processors, or protocol gateways, verify all software licenses and part numbers against official Siemens catalogs and confirmed through an authorized Siemens distributor quotation.

Engineer FAQ

Can I add the Huber regulator to HW Config without a GSD file?

No. HW Config strictly requires a GSD or GSDML file; non-PROFINET devices must be integrated via NetPro connections or communication blocks.

What is the difference between Open Communication and Modbus/TCP?

Open Communication (TSEND/TRCV) handles raw unformatted bytes, requiring custom parsing code. Modbus/TCP is a standardized industrial protocol with pre-built library blocks.

Does the PCS 7 Modbus/TCP library require a runtime license?

Yes. The Siemens PCS 7 Modbus/TCP block library requires a per-controller runtime license key activated via registration code.

Can an IPC 627 Microbox handle Modbus TCP communication?

Yes. The IPC 627 features integrated Gigabit Ethernet interfaces that support both Industrial Ethernet plant bus and third-party TCP sockets.

Technical References

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