Client Goal

Technical Goals:

• Integrate 4 independent control systems into 1 seamless system
• Coordinated servo control
• Coordinated drive control

Project Overview

The production process involved migrating a continuous flow of product from a singular pump to one of three unique packaging systems by means of a complex conveying system. The unique conveying system forms the product and supplies the specified product weight to the packaging system, where the product is cut and packaged. Weight is controlled by changing the speed relationship between adjacent components of the conveying system. Preliminary analysis of the control system identified the requirements for 29 axes of servo position control, 68 axes of variable frequency drive speed control, and 34 separate operator stations. The existing production process was divided into three separate control systems: two packaging systems with individual control and two conveying subsystems. Integration was planned for six phases that stretched over the year. The customer and project objectives lead to the following control system requirements: the control system architecture had to be flexible, scalable and expandable; PLC and motion control had to be highly integrated; the architecture and selected hardware had to provide easy integration, and a recipe-based HMI was required. All three systems had to be integrated and function as one. The control system architecture was based on a hierarchy of network communications. The communication architecture provided an essential foundation for meeting all of the project objectives. Four different levels of communications were implemented. Ethernet provided supervisory control and software support functions. One ControlNet network provided communications between processors and remote I/O racks. Twelve DeviceNet networks were used for device level communications. DH+ was used for HMI communications. The use of DeviceNet, which reduced wiring between the operator station and main control panel to one DeviceNet cable and one power wire, significantly reduced installation cost and time while increasing the flexibility of the control system. Unusually high speed requirements of one of the packaging systems dictated the need for a separate, dedicated ControlNet network for communication between the processor and associated remote I/O rack.

The control system electronically gears the drives together based on individual drive speeds stored in an HMI recipe system. The objective of the conveying system is to provide a uniform thickness of product to the packaging system as specified by the selected recipe. Each packaging system provides a master speed reference that determines the product flow rate for the conveying system. Analog sensors provide feedback to PID control loops that automatically adjust gear ratios to account for product variations. Operators can override automatic control of gear ratios or adjust gear ratios. The conveying system includes a subsystem that required four axes of servo position control. Since the subsystem was not to be installed until the second phase, a stand-alone control system was developed to allow full testing at the OEM facility. With highspeed gearing and coordination over ControlNet between the two Logix 5550 processors, product flows seamlessly through the subsytem. Three different PanelView 1000 HMI’s were developed – one for each packaging system and one for the conveying system. The HMI applications provide multiple user levels and functions. The HMI’s provide extensive status, diagnostics, and alarming information to the operator. The HMI’s have extensive recipe management for selecting, editing, and creating recipes. The packaging system required 22 axes of servo position control. Four axes are controlled by ControlLogix motion controllers interfaced with 1394 Servo Controllers. The four axes are electronically cammed together by the ControlLogix motion controllers to provide precision control. All motion instructions are executed by ladder logic in the Logix5550 processor. The ControlLogix motion controllers close the position loop and the 1394 Servo Controller closes the speed loop. Eighteen Ultra 1398 Servo Controllers were used in an indexing mode. The Ultra 1398 Servo Controllers were connected to a DeviceNet network to support setup and status monitoring functions. Previous packaging systems required an external Programmable Limit Switch module to control high speed discrete functions.

The speed and flexibility of the Logix5550 processor allowed the (PLS) functionality to be programmed within the software application. The packaging system uses a dedicated ControlNet network to provide high-speed communications between two I/O racks independent of the system-wide ControlNet network. The packaging system incorporates extensive diagnostics and safety services. These services protect the machine due to overlapping motion and provide safety for operators. The machine control, servo control, PLS control, and diagnostics are developed in a single programming language and executed by a single Logix5550 processor.

Scope of Supply

• New Technology Evaluation
• Process Optimization
• Scope Development
• Technology Comparison
• Vendor Management
• CAD Documentation
• Commissioning & Start-up
• Control Panel 
• Electrical Construction Management
• Electrical Control Design
• Electrical Power Distribution Design
• Human Machine Interface Development
• PLC Software Development
• System Training
• Emergency Support
• Support Agreements
• Engineering & Technical Staff Augmentation
• Remote Monitoring & Support
• Automation Hardware & Software Maintenance
• Training

The Outcome

Production Benefits

• Minimal installation time
• Rapid product changeover
• Improved product consistency
• Minimal product waste
• Increased system up time