5.5
Relay contact configuration
The function group RELAYS is only accessible for instruments equipped with the Plus packet.
The relay contacts described below can be selected and configured in any way (max. four
contacts depending on options installed):
• Limit contactor for measured oxygen value: R2 (1)
• Limit contactor for temperature: R2 (2)
• P(ID) controller: R2 (3)
• Timer for cleaning function: R2 (4)
• ChemoClean function: R2 (5)
5.5.1
Limit contactor for measured oxygen value and temperature
Liquisys M has several possibilities for using
a relay contact.
Switch-on and switch-off points and pickup
and dropout delays can be defined for the
limit contactor. Moreover, an alarm threshold
can be set to issue an error message and to
start a cleaning function.
These functions may be used for oxygen and
temperature measurement.
Please refer to Fig. 5.5 for a graphic
representation of the contact states of any
relay or alarm contact.
When the measured value increases (max.
function), the relay contact is closed at time t
2
when the switch-on point has been exceeded
(t
1
) and the pickup delay (t
2
– t
1
) has expired.
When the alarm threshold (t
3
) is reached and
the alarm delay (t
4
– t
3
) also has expired, the
alarm contact is switched.
When the measured value decreases, the
alarm contact is reset when the measured
value drops below the alarm threshold (t
5
).
The relay contact is also reset (t
7
, after the
dropout delay t
7
– t
6
).
When the pickup and dropout delays are set
to 0 s, the switch-on and switch-off points are
identical to the contact switching points.
Settings analogous to the max function can
also be made for a min function.
t
1
t
1
t
2
t
2
t
3
t
3
t
4
t
4
t
5
t
5
t
6
t
6
t
7
t
7
t
t
Alarm threshold
Alarm threshold
Switch-on point
Switch-off point
Switch-off point
Switch-on point
Measured value
Switch-on point > switch-off point: maximum function
Switch-on point < switch-off point: minimum function
Contact ON
Contact ON
Alarm ON
Alarm ON
Alarm OFF
Alarm OFF
Contact OFF
Contact OFF
GRENZ-E.CDR
Fig. 5.8
Depiction of
alarm functions
Instrument configuration
Liquisys M COM 223 F / 253 F
34
Hauser
