Magnetrol E3A Modulevel, Руководство по эксплуатации

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17 48-640 E3 Modulevel ® Displacer Level Transmitter - F
OUNDATION
fieldbus ™
4.0 Function Blocks
4.1 Overview
The E3 MODULEVEL Liquid Level Displacer Transmitter
operates on the Archemedes principle of buoyancy force.
Refer to Bulletin 48-635 for more detailed information on
the MODULEVEL transmitter.
The E3 MODULEVEL is a liquid level transmitter with
four F
OUNDATION
fieldbus ™ Blocks (one Resource Block,
one Transducer Block, one Analog Input Function block,
and one PID Function block. 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 user-defined
name.
The TRANSDUCER block output is available to the
network through the ANALOG INPUT block.
• The ANALOG INPUT block (AI) takes the TRANSDUCER
block level or density value and makes it available as an
analog value to other function blocks. The AI block has
scaling conversion, filtering, and alarm functions.
4.1.1 universal 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.