Endress+Hauser iTEMP TMT 165 FOUNDATION Fieldbus Betriebsanleitung Seite 141

FOUNDATION Fieldbus temperature transmitter
Index Parameter
47 ALARM_HYS
Endress+Hauser
PID Function Block (PID controller)
Write access with
operating mode
(MODE_BLK)
ROUT - RCAS - CAS - For entry of the hysteresis value for the upper and lower warning or alarm
AUTO - limit values. The alarm conditions remain active as long as the measured
MAN - OOS value is within the hysteresis.
The hysteresis value affects the following warning and alarm limit values of
the PID Function Block:
HI_HI_ALM
HI_ALM
LO_LO_ALM
LO_ALM
DV_HI_ALM
DV_LO_ALM
User input:
Factory default:
2
The hysteresis value relates to a percentage of the range of the parameter
group PV_SCALE in the PID Function Block (see page 153).
Example:
The top diagram shows the alarm limit values defined LO_LIM and HI_LIM
with their respective hystereses (gray background) and the signal curve of
the process variable PV.
The bottom two diagrams show the behaviour of the associated alarms
HI_ALM and LO_ALM in relation to the changing signal curve (0 = no alarm,
1 = alarm output).
Description
Upper limit value alarm
Upper limit value warning
Lower limit value alarm
Lower limit value warning
Limit value for upper control deviation
Limit value for lower control deviation
0...50%
0.5
Note!
a = Process variable PV exceeds the
limit value HI_LIM, HI_ALM is activated.
b = Process variable PV is below the hysteresis
value of HI_LIM, HI_ALM is deactivated.
c = Process variable PV is below the
limit value LO_LIM, LO_ALM is activated.
d = Process variable PV exceeds the hysteresis
value of LO_LIM, LO_ALM is deactivated.
11 Appendix
141