8.Power may be applied to the instrument when the installa- tion is complete and has been checked by the instrument engineer or safety officer.
3.0Function Blocks
3.1Overview
The Enhanced Jupiter Model 2xx is a level transmitter with four FOUNDATION fieldbus™ Function Blocks (one Resource Block, one Transducer Block, and two Analog Input blocks. The idea of Function Blocks, which a user can customize for a particular application, is a key concept of Fieldbus topology. Function Blocks consist of an algorithm, inputs and outputs, and a
The TRANSDUCER block output is available to the net- work through the ANALOG INPUT blocks.
•The ANALOG INPUT blocks (AI) take the TRANSDUCER block level values and makes them available as an analog value to other function blocks. The AI blocks have scaling conversion, filtering, and alarm functions.
3.1.1Universal Fieldbus Block Parameters
The following are general descriptions of the parameters common to all blocks. Additional information for a given parameter is described later in that specific block section.
ST_REV (static data revision): a read only parameter that gives the revision level of the static data associated with the block. This parameter will be incremented each time a static parameter attribute value is written and is a vehicle for tracking changes in static parameter attributes.
TAG_DESC (tag descriptor): a user assigned parameter that describes the intended application of any given block.
STRATEGY: a user assigned parameter that identifies groupings of blocks associated with a given network connec- tion or control scheme.
ALERT_KEY: a user assigned parameter which may be used in sorting alarms or events generated by a block.
MODE_BLK: a structured parameter composed of the actual mode, the target mode, the permitted mode(s), and the normal mode of operation of a block.
•The actual mode is set by the block during its execution to reflect the mode used during execution.
•The target mode may be set and monitored through the mode parameter.
9 |
