Challenge
Hallam-ICS was selected to design a large life safety system for a new semiconductor manufacturing facility using Rockwell PLCs and Ignition SCADA. This system’s primary role is to monitor for toxic gas leaks across the site and within a 350,000 square foot cleanroom.
This is a large system, including:
- 10 redundant pairs of Rockwell ControlLogix PLCs
- 46 Remote I/O panels
- 5 Redundant Ignition SCADA servers
- Approximately 12,000 IO points
The system architecture and software design are based upon three primary objectives:
- Quality. As a life safety system, there is a zero-tolerance policy for errors.
- Speed. Response/update time as well as efficiency of code development and deployment.
- Expansion. Expandability allowing the system to triple in size in the next 5 years.
Solution
Ignition was chosen for this project because of its scalability. The scale-out architecture allows for dedicated Ignition SCADAs to focus on certain tasks while allowing the SCADAs to communicate with each other quickly and seamlessly. Three Ignition servers are dedicated as data servers, communicating with PLCs and recording historical data to SQL. One Ignition SCADA is assigned as a front-end server, dedicated to hosting client sessions with fast response time and executing one-off SQL queries. Finally, one Ignition server is configured as an EAM (Enterprise Administration Module) server, allowing central monitoring of all the SCADAs, management and deployment of projects, and synchronization of UDTs and project information. The SCADA is designed to handle approximately 1.2 million tags, 450 screens, and a large amount of historical data collection. The majority of programming in both Ignition and the PLCs is being done using UDTs (user defined types for tags) and code templates to allow for speed of development and quality.
The Rockwell PLC system has been designed according to Rockwell’s best practices for redundant controllers. Redundant PLC systems have specific requirements around memory utilization (no more than 50%), types of tasks allowed, and types of instructions. Often these requirements are not obvious and can cause significant issues with system integrity over time. The system heavily uses UDTs and reusable code segments (AOIs). This allows for faster development and faster iteration for future changes. It also shrinks the size of the code allowing for less memory and CPU utilization enabling a cost savings on hardware. The PLC programming also includes a significant amount of error and fault detection and mitigation that is consistent with life safety systems.
