ולידציה – FDS – System Functions and Facilities
This article was written by Iian Shaya, validation,automation and control expert
.The Function Design Specification (FDS) is part of the validation documentation. In this article I will continue to elaborate the parts of the FSD of system function and the system facilities
Modes of Operation
This section details all modes of operation for the system, including
Automatic/Manual
Start-up/Shutdown
Overrides
Emergency Shutdown
System Failure and Recovery
Functional Operation
This section divides each of the sequential functions into logical areas (determined by the process), and provide complete description of each function, including
Normal Control Functions – such as normal sequencing, control, etc
Interlocks – details of all interlocks within the function
Alarms – lists of all associated alarms and actions for recovery
Operator Requirements
This section describes the interface between the operator and the detailed function. It is probably the most important to the user during the design phase, as it fully details all the functions to be supplied by the system in order to meet the user's requirements. It must be written clearly and concisely, so that operators and users without technical background can visualize the system to be supplied. Inputs from the user should be clearly detailed so that the operational requirements can be determined
Human/Machine Interface – HMI
This section describes in detail all points of operation, local terminals, remote terminal, message displays, pushbutton stations, etc
Where computerized interfaces are used, such as SCADA or HMI, a list of the screens and the proposed content should be included
Dynamic Attributes – dynamic color changes for status
Display Values – Values to be displayed on screen and resolution- No. of decimal places
Input Devices – Operator interaction devices, mouse, keyboard, touch screen, etc
Alarm and Event Displays
Security – Password Access
System Data
All the data gathered, generated or calculated by the system should be detailed. The detailed data should include
Type
Range
Accuracy/Resolution
Scaling
All the data to be stored should be detailed. This includes historical trend data, alarms and events, taking into consideration the following
Location of data to be stored – fixed disk, floppy disk, etc
Retention period – length of time for the data to be maintained
Data Archive – procedures for backup to removable medium
Data Export – export facilities to other formats, such as Excel, Access, Lotus, etc
System interfaces
This section provides complete details of all inputs and outputs from the control system. When separate I/O schedules are generated, these documents must be referenced in the FDS, or else, the complete schedules must be included in the FDS appendix
For digital and analog I/O, this section should provide details of voltage, current, etc., being specific where interfacing to 3rd party equipment. The signal states should be included as follows
Digital inputs – two states
False or Off
True or On
Analog inputs – detailed range
Detailed communication interfaces between systems should include protocols and formats, and also provide complete details of data to be transferred, paying special attention to 3rd party devices
This article was written by Iian Shaya, validation,automation and control expert
