© Tony Simmons 2010
Select the first letter of the word from the list above to jump to appropriate section of the glossary. If the term you are looking for starts with a digit or symbol, choose the '#' link.
Glossary of Automation & Control Engineering Terms
cGMP
Current Good manufacturing Practice.
CAN
Controller Area Network (CAN) is a serial bus system especially suited to interconnect smart devices to build smart systems or sub-systems. It has a maximum transmission rate of 1 Mbyte/sec.
The network's multi-master capabilities allow building smart and redundant systems without the need of a vulnerable master.
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the broadcast messaging guarantees 100% data integrity as any device within the network uses the same information,
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the sophisticated error detecting mechanism and the retransmission of faulty messages is the second enabler for 100% data integrity,
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The CAN protocol is an international standard defined in the ISO 11898. Conformance testing for the CAN protocol is defined in ISO 16845, which guarantees interchangeability of CAN chips
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CDMA
Code Division Multiple Access
Change
A change from the Requirement Specification by the Client or by Projects.
Change is one of three possible categories given to an observation raised by a Comment Sheet (see Comment Sheet).
Changes require Client approval and satisfactory agreement on the cost of the Change. Changes will then become part of the Change control philosophy (see Change Control).
The Change is cross referenced to the relevant correspondence pertaining to the implementation of the Change.
This is the operation of applying changes, with suitable authorisation, to establish new states through which the project passes. Significant states - baselines - are related to milestones defined in the System Project Plan; in addition, a number of minor states may be identified between baselines. The authorisation required to establish a change allows the continuous application of quality assurance procedures throughout the project. Change control can therefore be regarded as essentially an aid to management by providing the visibility necessary to monitor and control the progress of a project.
Change Note
A document specifying the details of an authorised change request. [GAMP]
Change Plan
A plan defining the details of the authorised change request, defining actions, responsibilities and procedures. [GAMP]
CHAZOP
Computer HAZOP. The term was coined by ICI and refers to the HAZOP of a process from the perspective of computer controlled operations. In particular it is used to determine the demand rate on a protection system in the event of process control system failure.
Checking
Three types of checking are employed to trap out errors introduced into the design by "fallible" humans:-
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"Testing" -
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"Verification" checking that the transformation from one process (activity) output to the next has been correctly done, i.e. life cycle stage-
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"Validation" checking that the system meets the client's needs, i.e. life cycle stage-
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CIM
Computer Integrated Manufacture - a term used to describe the integration of a company's process control and management systems to link the needs of production control and sales. See also MES.
Class
A template for defining the methods and variables for a particular type of object. All objects of a given class are identical in form and behaviour but contain different data in their variables.
Client/Server model
As in Client/Server computer architectures. In the case of a network of diskless personal computers or workstations that are communication over a network with a File Server having a disk on which all the files are stored, these PCs are known as Clients. In such a system, clients access their data by sending requests to the server, which carries out the work and sends back the replies. Communications always take the form of request-reply pairs, always initiated by the clients, never the server. This model is called the Client-Sever model.
CNC
Computerised Numerical Control.
CNI
Communication Network Interface
CoP
Control & Operability Philosophy
Code
"Code" is the term used to describe the instructions given to programmable equipment to cause the required set of actions or calculations to be performed.
"Source" code is the term given to program instructions in the form of readable and usually annotated text files which are then "assembled" or "compiled" to create "object" or "executable" code which the processor actually runs to perform its tasks.
A form on which observations are recorded about System Operation/Performance during Module/Integration/Works Acceptance/Site Acceptance testing.
The comment sheet will also record which part of the system is affected (e.g. database, mimics, etc.) and allow for appended signatures to demonstrate the required modification has been carried out and tested.
The comment sheet contains a brief statement or reference to the proposed solution.
A database is used to manage the Comment Sheet status.
See also Test Observation Note
Competent
Having the necessary skills, knowledge, understanding, and maturity of judgement to be able to discharge the stated responsibilities safely and effectively.
Refer to the BCS/IEE Safety, Competency and Commitment - Competency Guidelines for Safety-related Systems Practitioners, 1999.
Compiler
A program used to translate a higher order language (source code) into its re-locatable or absolute machine code equivalent (object code). [ANSI/IEEE]
Complexity
When used in connection with safety systems - an indicator of the number of degrees of freedom for making mistakes.
Configuration
This term is unfortunately used in two totally different ways in the process control industry so great care should be taken in its use.
The process control industry has adopted the term "configure" (verb) to mean the entering of data and settings into a standard control software package in order to customise the package for use on a given plant. In this context, the word "configuration" is the act of configuring such a system.
In software engineering terminology, the word "configuration" noun) is a collection of "versions" with some common purpose. Configuring is the process of building a particular configuration.
BS 6488 defines "configuration" as - "the totality and inter-relationship of hardware, software, firmware, services and supplies required for the successful operation of a computer-based system or associated group of systems at a given reference point in time."
Configuration - the documented physical and functional characteristics of a particular item or system. A change converts one configuration onto a new one. [GAMP]
Configuration Control
This is concerned with the building of appropriately structured systems from their constituent parts. See Configuration Management
Configuration items shall have unique names and must be clearly identifiable.
A configuration "item" is any entity within a configuration whose development is to be controlled and tracked by configuration management. Items have a development history which is relevant to the project and this requires recording so that any item, may be reconstructed in one of its former states. Items can be elementary objects, such as simple text files, or composite objects such as libraries.
The purpose of configuration management is to ensure that, at all times, the status of all versions of all development products is known and that the status of shared objects is carefully controlled and all unauthorised changes are prevented. CM may also be extended to record the reason for changes in passing from one version to the next.
The controlled intermediate products (baselines), and the milestones at which they are established, form a unifying link between the control of the software "process" and the control of the software "product". The status of, and access to, the intermediate products are strictly controlled but CM also means that:-
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only the controlled versions can be used as input to other activities
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any proposed changes to the baselines must be processed through the formal change procedures
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The IEEE standards define software configuration management as the process of:-
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identifying and defining the configuration items in a system;
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controlling the release and change of these items throughout the system life cycle;
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recording and reporting the status of configuration items and change requests;
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verifying the completeness and correctness of the configuration items.
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CM comprises three aspects:
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version and variant control
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configuration control
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change control
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Good CM relies heavily on version control; it is concerned with combinations of items, their relationships and their attributes. As a minimum, the relationships of "part/part-of" and "uses/used-by" must be handled, as these define the structure of composite items and their dependencies. The most significant attribute of an item is its current "status" (inspection level) which indicates the degree of confidence in its accuracy or completeness. Another is a statement of the operation(s) required to build a new version of the item.
Configuration Status Accounting
The recording of all configuration item descriptions together with the status of proposed changes to the system and the implementation state of proposed changes.
Control & Operability Philosophy
A document produced to document the high level philosophies of how a plant will operate. These will include such matters as local versus central control room operations, the starting of motors, to the extent of automation. It will document the philosophy for integrating package equipment controls into the overall control system.
It is a pre-cursor of the Requirements Specification
It is a pre-
CIP
Term used in the pharmaceutical, brewing, dairy and food industry to describe the Cleaning-In-Place of equipment and pipes to prevent build up of contamination.
Cross Connection
This refers to the connection between the signal pairs arriving from the field to the cable pairs connecting to the computer Input/Output channels. Signals arrive in the control building usually gathered in multi-cores dictated by geographic location of the field devices in the plant. The signals need mapping into groups suited to functional requirements rather than geographical. This is done in the marshalling (field termination) cabinets.
