Position: In the past two years since the launch of the Generation 3 instrumentation range the capability of the TAD 3 weight controller and indicator has been constantly explored and extended in response to the application needs of its markets.One of the major areas of development has been in the field of batch control,and Batch control used in weight controller and indicator.
A flexible weighing systems based approach is an essential requirement to meet the diverse needs of the industrial process weighing market at a reasonable cost and the TAD 3 rises well to this challenge.
The basic building blocks of a TAD 3 based system facilitates digital and analogue I/O as well as versatile data communication links.
Coupled to this, the Thermo Nobel ability to be able easily to configure and modify the standard software modules that lie at the heart of the instrumentation provides a powerful set of system tools.
Automatic batching systems can be configured to operate and monitor valves, pumps and agitators in configurable sequences to control batch production processes, where the central measurement is based on weight.
The software within the TAD 3 is the result of many years of experience and not only provides batch control actions that work under normal operating conditions, but are carefully thought out to provide predictable behaviour when the abnormal happens.
The software is robust and fault conditions are recovered gracefully.
The TAD 3 batching software can also be used as a semi-automatic or even totally manual operator aid.
Such a system can be illustrated by a recent example.
A manufacturer of pizza needed equipment to guide the operator through a sequence of actions involving the weighing, mixing and cooking of various recipes used as the toppings for the final product.
The TAD 3 was specially configured around the manufacturing procedures already in place.
In this way, the user obtained equipment that would help ensure product quality and the company and its staff could feel comfortable with.
The operator is able to select one of a number of pre-programmed recipes.
The person is enabled to adjust the total required batch size but not the proportions of the ingredients that make up that batch.
The weight controller then proceeds through the batch sequence, providing clear on-screen instructions to prompt the operator.
Hardware outputs activate peripheral plant items that control the mixing and cooking activities.
Communications between the operator and the weighing system can be greatly improved by the use of graphic displays.
The advanced data communication facilities within the TAD 3 are specifically organised to allow direct external access to all the measurement and batch control data held in the weight controller.
This is well illustrated here where the weight and status of the information held in the weighing instrument is made available to the operator in active schematic form.
The TAD 3 is being developed further to increase its memory and therefore its capabilities.
The new release will handle at least 20 separate ingredients or other activities and be able to store 30 recipes.
Many industrial applications require even greater capability.
The Thermo Nobel solution to this need is to use the undoubted power of the PC or the PLC.
The problem with some PC based applications relates to the dependability of the software and the operating systems and machines used to run that software.
An industrial weighing control system must have a robust platform for obvious reasons.
For this reason, Thermo Nobel is developing a number of software links that can be used in conjunction with PC applications to provide memory, operator interfaces and data handling but that still uses its own dedicated hardware to interface with the plant.
This philosophy maximises the potential functionality of the weighing control systems, whilst ensuring that the safety or operation of the users plant will not be compromised.
The first stage in this development is already implemented as a PC software package called BatchView.
This program facilitates monitoring and the basic batch controls of the TAD 3 weight controller from a computer (Figure 3).
Set points can be changed and the batch control can be initiated and viewed from the computer but the actual sequences and control functions are embedded in the weight controller.