YOKOGAWA F3CU04-0S, User Manual

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C2-20
IM 34M06H62-02E 2nd Edition : June 2008-00

Heating/Cooling Control Output Limits
The upper limit of the heating output is defined with the Upper Output Limit (n.OH)
parameter (where n: 1-4), and the upper limit of the cooling output is defined with the
Lower Output Limit (n.OL) parameter (where n: 1-4). The lower limit of the heating or
cooling output is fixed at 0%.
Table C2.18 Heating/Cooling Control Output Limits
Data Position Number
Symbol Description Unit Data Range
Default
Value
Attribute Stored
Loop 1 Loop 2 Loop 3 Loop 4
209 409 609 809 1.OH Upper output limit
% 0 to 1050 (0.0 to 105.0%)
1000 RW

210 410 610 810 1.OL Lower output limit 1000 RW

229 429 629 829 2.OH Upper output limit
% 0 to 1050 (0.0 to 105.0%)
1000 RW

230 430 630 830 2.OL Lower output limit 1000 RW

249 449 649 849 3.OH Upper output limit
% 0 to 1050 (0.0 to 105.0%)
1000 RW

250 450 650 850 3.OL Lower output limit 1000 RW

269 469 669 869 4.OH Upper output limit
% 0 to 1050 (0.0 to 105.0%)
1000 RW

270 470 670 870 4.OL Lower output limit 1000 RW

In Automatic mode, depending on the dead band and cooling gain preset values,
sometimes the cooling output will never reach the Lower Output Limit (n.OL) (n: 1-4).
TIP
In Automatic mode of heating/cooling PID control, the output range is defined by restricting the PID
computation result within upper and lower limits that are calculated from the specified upper and lower
output limits as follows:
- Upper limit for PID computation result =
upper output limit (n.OH) (n: 1-4)/2 + dead band [%]/2 + 50%
- Lower limit for PID computation result =
50% - lower output limit (n.OL) (n: 1-4)/(2 x cooling gain) - dead band [%]/2
where the dead band is converted from industrial unit to percentage as follows:
Dead band [%] = ((dead band in industrial unit)/(PRH - PRL) x 100%) x 100%/(proportional band x 2).
The PID computation result is further restricted within

200%. Therefore, even if the computed lower
limit for PID computation result is less than -200%, the PID computation result is still limited by -200%
and so is the cooling output.