Distributed Control Systems - Part B Vocabulary

Flashcards covering vocabulary from the Distributed Control Systems - Part B lecture notes.

Function Block

A self-contained block of code that performs tasks essential to process control.

P&ID

Pipe and Instrumentation Diagram, the source of required tasks that function blocks perform.

Foundation Fieldbus

Developed a complete control system architecture to enable distribution of control functions into field equipment that use function blocks.

Technology Block

Knows the details of the instrument and performs the conditioning required to provide the sensor value to the function blocks/makes the change in the output as dictated by the function block.

Resource Block

Specifies the instrument type, revision, manufacturer ID, serial number and resource state.

Function Block Instance

Graphically represented as a block with the function block name inside and the instance name above the block.

Input Parameters

Receive data from another block

Output Parameters

Send data to another block

Contained Parameters

Internal to the function block and do not appear as normal input and output parameters.

Algorithms

Programs that the function block executes using the input and contained parameters to determine the value of its output parameters.

Manual (Man) Mode

The block output is not calculated, but is directly set by the operator through an interface device.

Automatic (Auto) Mode

The algorithm uses a local setpoint value to determine the output value.

Cascade (Cas) Mode

The algorithm uses a setpoint value supplied by another function block through the cascade input parameter to determine the output value.

Initialization Manual (IMan) Mode

The block output is set in response to the status and value of its back calculation input parameter.

Out of Service (OOS) Mode

The block is not being executed. The output and setpoint are maintained at their last values.

Local Override (LO) Mode

The block output is set to track the value of its tracked input parameter.

Wire Link

A line that indicates function block communication.

Quality

Classified as Good Cascade, Good Non-Cascade, Uncertain, or Bad, indicating the reliability of the parameter value.

Sub-status

A complement of the quality status, providing information to initialize cascade communication or information on alarms (e.g., Non-specific, Not connected, Sensor failure, Active block alarm, Engineering unit range violation).

Limits

Indicates whether the associated value is limited (Not limited, High limited, Low limited, Constant).

Cascade Initialization

The communication that occurs between cascade blocks as the downstream blocks mode changes from manual to auto to cascade.

NAMUR Compliant

Analog transmitter sets its current signal outside its normal range limits (below 3.6 mA or above 21 mA) to flag its failure.

Control Module

A control strategy, typically with a unique name corresponding to the names used on the P&ID.

Alias Tag Name

Given to each channel of an analog input channel, such as LT101 (level transmitter 101).

HARTFIELDVAL

The 4 mA to 20 mA signal converted to engineering units

HART_PV

The transmitter's primary variable read digitally

HART_SV

The transmitter's secondary variable read digitally

HART_TV

The transmitter's tertiary variable read digitally

HART_FV

The transmitter's fourth variable read digitally

Increase to Close

An IO_OPTS setting used so that when the operator sends a zero percent signal to the control valve, it closes.

State Name

Defines a specific action (e.g., OPEN or CLOSE for a block valve).

Permissive

Any condition that must be TRUE before a device can be activated.

Interlock

Any condition that must remain TRUE for a device to stay active.

Named Sets

When state names are used in combination.