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Figure 3.3 – analog input block – Flowserve MX/QX Profibus DP/PA Field Unit User Manual

Page 42

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PB DPV1 / PA Field Unit Installation and Maintenance FCD LMENIM2336-03 – 12/12

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Figure 3.3 – Analog Input Block

Analog Input Function Block

Enable

Simulate

Valve and

Status

FB Algorithm

Operator

Value Status

Value

Off

On

Value Status

Limit

Check

Fail Safe

MODE- and STATUS-

Handling

OUT

OUT

Operator

AUTO

Status

MAN

Out of

Service

OUT

Simulate Parameter

Acyclic Configuration Parameters

PV from Transducer

Block Selected Channel

Typical for Valve Position,

Analog Input #1,

Analog Input #2

Cyclic Process

Parameter to

Network User

The AI standard function block supports alarming, signal scaling, signal filtering, signal status
calculation, mode control, and simulation per the PROFIBUS PA Profile, Version 3.0 specifications.
In Automatic Mode, the block’s output reflects the Process Variable (PV) Value and Status. In Manual
Mode, the Output parameter may be set manually by the operator. Manual Mode is reflected by the
output Status. The output Status can also be used to generate alarms.

Output
OUT (cyclic) is the block output value and status. It is a process parameter used during runtime and
therefore is cyclic data.

Scaling
Conversion of the Process Variable into percent using the High and Low scale values. The engi-
neering unit of PV_SCALE (acyclic) high and low scale values is directly related to the PV_UNIT
(acyclic) of the configured transducer block (configured via the Channel parameter). The PV_SCALE
high and low scale values follow the changes of the PV_UNIT of the related transducer block auto-
matically, i.e., a change of the transducer block PV_UNIT causes no bump at OUT from the AI Block.

The function block parameter OUT_SCALE (acyclic) contains the values of the lower limit and upper
limit effective range, the code number of the engineering unit of the Process Variable and the number
of digits on the right-hand side of the decimal point.

Supported Modes of an AI Function Block
• Out of Service (O/S): The AI FB is not able to fulfill its functional calculations anymore (e.g. the

parameter values in the non-volatile memory are not accessible after a reset).

• Manual (Man): The operator writes directly to the OUT parameter of the AI FB with a configuration

tool.

• Automatic (Auto): The AI FB processes the value from the transducer block channel data according

to all algorithms (scaling, filtering, status and mode calculation, limit checks).