Author contributor: Project Engineer Amjad AbouShama
E Tech Group is currently in the final stages of developing a design that interfaces with Inductive Automation’s Ignition, to support batch control while meeting ISA-88 standards. The resulting design will give batch control manufacturers access to Ignition’s open architecture, cross-platform compatibility, user-friendly development environment and flexible licensing model while meeting the strict ISA-88 standard. Additionally, the design will free manufacturers from relying on the far more expensive and proprietary Distributed Control Systems (DCS).
ISA-88: The Industry Standard for Batch Control
The ISA-88 Standard, also known as the International Society of Automation Standard 88 for Batch Control, provides guidelines and best practices for the design, implementation and operation of batch control systems in manufacturing processes. The standard makes it easier to achieve interoperability, consistency, and efficiency in batch manufacturing. Meeting the ISA-88 standard is one of the primary requirements of meeting Good Manufacturing Practice (GMP) standards. Therefore, it is particularly relevant in industries where batch processes are regulated:
- Pharmaceutical
- Food and beverage
- Biotechnology
- Chemical
The standard devises a platform-independent means to consistently present information related to a batch control system. It defines models for both the physical equipment (Physical Model) and the procedural control (Procedure Model) involved in batch manufacturing. Terminology is standardized and the specification lays out a design, independent of the specific process or data in use. One of the primary intents of the standard is to help engineers optimize a batch process.
ISA-88 Compliant Batch Control Built on Ignition
E Tech Group has used Ignition’s Vision module to implement the physical and procedural models within the ISA-88 standard. The physical model describes the actual equipment and devices being used while the procedural model ensures that the process occurs in a consistent and repeatable manner through defining process execution models and batch recipes. The physical model has a three-tier hierarchical structure of control modules. Together, they define the specific details about a device in use (i.e. liquid sensor), its relationship and integration with equipment (i.e. a liquid sensor that measures the fluid level in a tank), and their capabilities as a unit. In addition, the unit includes sequential flow chart programming capabilities for the coordination of tasks (i.e. moving liquid between two tanks). These programming capabilities are called a “phase logic” within the ISA-88 standard. The figure 1 below displays the phase logic display that is used to control the running phase.
E Tech Group’s batch control is built based on the Ignition Vision Module and Ignition SFC Module. As well as the design utilized Project Library Scripting and Named Queries features in Ignition to manage codes and queries. However, the design utilizes UDT Definitions and SQL database to build the physical model hierarchy as defined in the ISA-88 standard as control modules, equipment modules, units, process cells, and areas. Figure 2 below displays an instance of Unit UDT Definitions that utilizes multiple control modules, equipment modules, and phase logics UDTs within it to define devices and functionality of Mixing Tank T-101. Finally, for every phase logic built into a unit, the design utilizes 5 SFC charts to build Phase running, holding, restarting, aborting, and stopping transitional states as shown in Figure 3 below.
E Tech Group’s engineers will help your automation team in installing and configuring the Ignition platform to interact with your process. Besides the Inductive University credential-free course, E Tech Group would provide specialized training to your engineers on configuring and troubleshooting the batch control design.
Cost-Effective Batch Control Meeting ISA-88 Standards
The project addresses all of the ISA-88 standards. Because it is based on the Ignition platform, it will be highly cost-effective while simultaneously taking advantage of the platform’s strengths and versatility.
Simpler Licensing Model Offers Design Flexibility
By integrating the design with the Ignition platform, E Tech Group’s solution will be far less costly than other options, including a more mature and proprietary DCS. Ignition’s licensing is sold by module, allowing the user to pay for needed functionality with unlimited tags and designer clients without further licensing costs. In contrast, users of DCS are often charged an annual subscription fee while also being charged based on the number of clients and tags in the system. The overall implementation cost difference is staggering. An example described below illustrates this difference numerically.
Hardware Flexibility
Ignition’s web-based integrated software platform supports redundancy and is platform-independent. It runs on all operating systems and is compatible with industry-standard hardware and equipment. It communicates to field devices using OPC protocols, and it connects to any SQL database. These features allow significantly more flexibility than using a DCS, which is primarily designed to work with the DCS’s own proprietary controllers, I/O modules, and field devices.
Batch Control via Ignition
In meeting standard DCS functionalities, such as E Tech Group’s implementation of Batch control, Ignition is still more cost-effective versus other DCS platforms. As an example, a recent version upgrade for a DCS manufacturer incurred costs exceeding $1M. Although the upgrade encompassed a new controller and a few other incidental hardware upgrades, the primary expense was attributed to engineering design fees. In contrast, transitioning to an Ignition-based solution is estimated to cost approximately $250,000, offering substantial savings.
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