WIKA T53 - Manual (Page 32)

3
This .status .is .a .copy .of .IN’s .status .unless .IN .is .good .and .there .is .a .PV .or .block .alarm . .
.
The .full .cascade .SP .sub-function .is .used, .with .rate .and .absolute .limits . .There .are .additional .
control .options .which .will .cause .the .SP .value .to .track .the .PV .value .when .the .block .is .in .an .
actual .mode .of .IMan, .LO, .Man .or .ROut . .Limits .do .not .cause .SP-PV .tracking . .
.
There .is .a .switch .for .BYPASS, .which .is .available .to .the .operator .if .the .Bypass .Enable .con-
trol .option .is .true . .Bypass .is .used .in .secondary .cascade .controllers .that .have .a .bad .PV . .The .
Bypass .Enable .option .is .necessary .because .not .all .cascade .control .schemes .will .be .stable .
if .BYPASS .is .true . .BYPASS .can .only .be .changed .when .the .block .mode .is .Man .or .O/S . .While .
it .is .set, .the .value .of .SP, .in .percent .of .range, .is .passed .directly .to .the .target .output, .and .the .
value .of .OUT .is .used .for .BKCAL_OUT . .When .the .mode .is .changed .to .Cas, .the .upstream .
block .is .requested .to .initialize .to .the .value .of .OUT . .When .a .block .is .in .Cas .mode, .then .on .the .
transition .out .of .bypass, .the .upstream .block .is .requested .to .initialize .to .the .PV .value, .regard-
less .of .the .»Use .PV .for .BKCAL_OUT« .option . .
.
GAIN, .RESET, .and .RATE .are .the .tuning .constants .for .the .P, .I, .and .D .terms, .respectively . .Gain .
is .a .dimensionless .number . .RESET .and .RATE .are .time .constants .expressed .in .seconds . .
There .are .existing .controllers .that .are .tuned .by .the .inverse .value .of .some .or .all .of .them, .
such .as .proportional .band .and .repeats .per .minute . .The .human .interface .to .these .parame-
ters .should .be .able .to .display .the .user’s .preference . .The .Direct .Acting .control .option, .if .true, .
causes .the .output .to .increase .when .the .PV .exceeds .the .SP . .If .false, .the .output .will .decrease .
when .the .PV .exceeds .the .SP . .It .will .make .the .difference .between .positive .and .negative .feed-
back, .so .it .must .be .set .properly, .and .never .changed .while .in .an .automatic .mode . .The .setting .
of .the .option .must .also .be .used .in .calculating .the .limit .state .for .BKCAL_OUT . .
.
The .output .supports .the .feed .forward .algorithm . .The .FF_VAL .input .brings .in .an .external .val-
ue .which .is .proportional .to .some .disturbance .in .the .control .loop . .The .value .is .converted .to .
percent .of .output .span .using .the .values .of .parameter .FF_SCALE . .This .value .is .multiplied .by .
the .FF_GAIN .and .added .to .the .target .output .of .the .PID .algorithm . .If .the .status .of .FF_VAL .is .
Bad, .the .last .usable .value .will .be .used, .because .this .prevents .bumping .the .output . .When .the .
status .returns .to .good, .the .block .will .adjust .its .integral .term .to .maintain .the .previous .output . .
.
The .output .supports .the .track .algorithm . .
.
There .is .an .option .to .use .either .the .SP .value .after .limiting .or .the .PV .value .for .the .BKCAL_
OUT .value . . .
4 .5 .Supported .Modes
O/S, .IMan, .LO, .Man, .Auto, .Cas, .RCas, .and .ROut .
4 .6 .Alarm .Types
Standard .block .alarm .plus .standard .HI_HI, .HI, .DV_HI, .DV_LO, .LO, .and .LO_LO .alarms .ap-
plied .to .PV .
4 .7 .Mode .Handling
Standard .transition .in .and .out .of .O/S . .
4 .8 .Status .Handling
Standard, .plus .the .following .things .for .the .control .selector .If .Not .selected .is .received .at . .
BKCAL_IN, .the .PID .algorithm .should .make .necessary .adjustments .to .prevent .windup .
4 .9 .Initialization
Standard .