WIKA T53 - Manual (Page 28)

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3.0 Analogue Input Blocks
T53 .has . .Analogue .Input .Blocks .to .be .configured .individually . .The .constrcution .of .the .
Blocks .is .in .line .with .the .standards .from .FOUNDATION .Fieldbus .and .Profibus .Nutzerorgani-
sation .respectively, .and .producer .specific .parameters .have .not .been .added . .However, .the .
Analogue .Input .Blocks .for .Fieldbus .Foundation .and .Profibus .are .dissimilar .due .to .the .para-
meter .differences . .
3.1 Analogue Input Blocks, Fieldbus Foundation
3 . .Overview
The .AI .block .takes .the .manufacturer’s .input .data, .selected .by .channel .number, .and .makes .it .
available .to .other .function .blocks .at .its .output .
3 .3 .Analogue .Input .Block .Schematic
3 .4 . .Description
Transducer .scaling .(XD_SCALE) .is .applied .to .the .value .from .the .channel .to .produce .the .
FIELD_VAL .in .percent . .The .XD_SCALE .units .code .must .match .the .channel .units .code .(if .one .
exists), .or .the .block .will .remain .in .O/S .mode .after .being .configured . .A .block .alarm .for .units .
mismatch .will .be .generated . .The .OUT_SCALE .is .normally .the .same .as .the .transducer, .but .
if .L_TYPE .is .set .to .Indirect .or .Ind .Sqr .Root, .OUT_SCALE .determines .the .conversion .from .
FIELD_VAL .to .the .output . .PV .and .OUT .always .have .identical .scaling . .
.
OUT_SCALE .provides .scaling .for .PV . .The .PV .is .always .the .value .that .the .block .will .place .in .
OUT .if .the .mode .is .Auto . .If .Man .is .allowed, .someone .may .write .a .value .to .the .output . .The .
status .will .prevent .any .attempt .at .closed .loop .control .using .the .Man .value, .by .setting .the .
Limit .value .to .Constant . . .
The .LOW_CUT .parameter .has .a .corresponding .“Low .cutoff” .option .in .the .IO_OPTS .bit .
string . .If .the .option .bit .is .true, .any .calculated .output .below .the .low .cutoff .value .will .be .
changed .to .zero . .This .is .only .useful .for .zero-based .measurement .devices, .such .as .flow . .The .
PV .filter, .whose .time .constant .is .PV_FTIME, .is .applied .to .the .PV, .and .not .the .FIELD_VAL . . .