PowerFlow Paper Solutions

System Architecture

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System Architecture

The Dilution Control System implements a closed-loop control architecture that continuously monitors the paper web's basis weight profile and adjusts dilution water flow to maintain uniformity across the web width.

Scanner/QCS
Measures basis weight profile
→
Dilution Control Software
Profile processing & control algorithm
→
PLC/Controller
Actuator control signals
→
Dilution Valves
Zone-by-zone water flow
Paper Web (Process) ← Feedback Loop

Hardware Components

The complete system consists of the following hardware components:

Control Station

  • Industrial PC: Runs the Dilution Control Software
  • Display: Operator interface for monitoring and control
  • Network Switch: Connects to QCS, PLC, and plant network

Measurement System

  • QCS Scanner: Traverses the paper web measuring basis weight
  • Scanner Interface: Provides profile data to the control system

Actuator System

  • Dilution Header: Distributes dilution water across zones
  • Proportional Valves: Control water flow to each zone (typically 24-96 zones)
  • I/P Converters: Convert electrical signals to pneumatic pressure
  • Position Feedback: Reports actual valve positions

PLC/Controller

  • PLC: Siemens, Beckhoff, Festo, or Modbus-compatible controller
  • I/O Modules: Analog outputs for valve control, analog inputs for feedback

Software Architecture

The Dilution Control Software is built with a modular architecture:

Communication Layer

  • Modbus TCP/RTU Client
  • Scanner Interface
  • Data Manager

Control Engine

  • Profile Processor
  • Control Algorithm
  • Constraint Handler

User Interface

  • Profile Visualization
  • Zone Control Panel
  • Configuration Dialogs

Support Functions

  • Alarm Manager
  • Grade Manager
  • Flushing Controller

Control Loop

The control loop executes at a configurable interval (default: 60 seconds) and performs the following steps:

  1. Read Scanner Profile

    Receive the latest basis weight profile from the QCS scanner via Modbus or direct interface.

  2. Process Profile

    Apply edge detection, spike removal, hole filling, and exponential filtering to clean the profile data.

  3. Map to Zones

    Convert scanner databoxes (typically 200) to actuator zones (typically 48) by averaging.

  4. Calculate Error

    Compute the difference between target profile and measured profile for each zone.

  5. Apply Control Algorithm

    Calculate position changes using the response matrix and control gain. Apply deadband filtering.

  6. Apply Constraints

    Enforce position limits, stepping limits, bending limits, and adjacent zone difference limits.

  7. Write Setpoints

    Send new valve setpoints to the PLC via Modbus for zones in AUTO mode.

Network Topology

A typical installation uses the following network architecture:

Network Recommendation

Use a dedicated industrial Ethernet network for control communication, separate from office networks. This ensures reliable, low-latency communication with the PLC and QCS systems.

Device Typical IP Address Port Protocol
Dilution Control PC 192.168.1.10 - Client
PLC (Festo/Generic) 192.168.1.100 502 Modbus TCP
QCS Scanner Interface 192.168.1.50 502 or Custom Modbus TCP / Vendor
Beckhoff EK9000 192.168.1.41 502 Modbus TCP
Siemens S7 PLC 192.168.1.30 102 S7-TCP