Ascon Tecnologic - K31D - OPERATING INSTRUCTIONS - PAG. 10
5.11 Alarms Output Functions
(AL1, AL2, AL3)
For the alarms operation settings, the operation of which is relat-
ed to the Process Value (
AL1
,
AL2
,
AL3
) it is first of all manda-
tory to determine to which output the alarm must be addressed.
To obtain this, it is necessary to set, in the parameters group
]
out
, the parameters related to the output that is to be used
by each alarm (
O1F
,
O2F
,
O3F
,
O4F
):
ALno
If the alarm output must be
ON
when the
alarm
is
ac-
tive
, while it is
OFF
when the
alarm
is
not active
;
ALnc
If the alarm output must be
ON
when the
alarm
is
not
active
, while it is
OFF
when the
alarm
is
active
(the
LED on the display shows the alarm status);
ALni
Same operation as
ALnc
, but with a reversed LED
indication (LED ON = Alarm OFF).
Note:
All the examples that follow are referred to alarm
AL1
.
Obviously the functions of the other alarms are similar
(change 1 with 2 or 3).
Access at the group
]
Al1
and program
oAL1
, to indicate
which output the alarm signal must to be sent.
The
AL1
alarm functioning is instead defined by parameters:
PrA1
Which Process Value must be used by AL1;
AL1t
Alarm type;
Ab1
Alarm configuration;
AL1
Alarm threshold;
AL1L
Low alarm threshold (for band alarm) or minimum Set
Point of
AL1
alarm threshold (for low or high alarm);
AL1H
High alarm threshold (for band alarm) or maximum Set
Point of
AL1
alarm threshold (for low or high alarm);
HAL1
Alarm
AL1
Hysteresis;
AL1d
Alarm activation delay (in seconds);
AL1i
Alarm behaviour in case of measurement error.
PrA1
- Alarm process measurement
Through this parameter it is possible to set the Process Vari-
able used by the alarm for operating. In fact the alarm can
operate considering the process variable as the value meas-
ured by Input 1 (
Pr1
), the value measured by Input 2 (
Pr2
),
the difference between the two inputs Pr1-Pr2 (
P1-2
) or can
consider the difference between the two inputs Pr1-Pr2 but
with a maximum limit and a minimum limit for the Pr2 meas-
urement Pr2 (
P1-L
).
AL1t
- Alarm Type
The alarm output can behave in six different ways:
–
LoAb
=
Absolute low alarm
: The alarm is
activated
when
the
PV
goes
below
the alarm
threshold
set at parameter
AL1
and
deactivated
when the PV goes
above
the value
[
AL1
+
HAL1
]. With this mode is possible to program, with
AL1L
and
AL1H
parameters, the minimum and the maxi-
mum limits of
AL1
thresholds.
–
HiAb
=
Absolute high alarm
:
The
alarm
is
activated
when the PV goes above the alarm
threshold set at parameter
AL1
and is
deactivated
when
thePV goes
below
the value [
AL1
-
HAL1
]. In this way is
possible to program, with
AL1L
and
AL1H
parameters, the
minimum and the maximum limits of
AL1
thresholds.
LoAb
OUT
AL1
AL1
PV
HAL1
time
HiAb
off
off
off
OUT
AL1
AL1
PV
HAL1
time
off
off
off
ON
ON
ON
ON
–
LodE
=
Deviation low alarm
: The alarm is
activated
when
the process value goes
below the value
[
SP
+
AL1
] and is
deactivated
when it goes
above the value
[
SP
+
AL1
+
HAL1
].
In this way is possible to program, with
AL1L
and
AL1H
param-
eters, the minimum and the maximum limits of
AL1
thresholds.
–
HidE
=
Deviation high alarm
: The alarm is
activated
when
the process value goes
above the value
[
SP
+
AL1
] and is
deactivated
when it goes
below the value
[
SP
+
AL1
+
HAL1
].
In this way is possible to program, with
AL1L
and
AL1H
param-
eters, the minimum and the maximum limits of
AL1
thresholds.
-AL1
Lode
OUT
AL1
SP
AL1
SP
PV
HAL1
time
Hide
off
off
off
OUT
AL1
PV
HAL1
time
off
off
off
ON
ON
ON
ON
–
LHAb
=
Absolute band alarm
: The alarm is
activated
when the PV goes
under the alarm threshold
set at pa-
rameter
AL1L
or goes
above the alarm threshold
set with
parameter
AL1H
and is
deactivated
when the PV returns
inside the range
[
AL1H
-
HAL1
÷
AL1L
+
HAL1
].
–
LHdE
=
Deviation band alarm
: The alarm is
activated
when the PV goes
below the value
[
SP
+
AL1L
] or
above
the value
[
SP
+
AL1H
] and is
deactivated
when the PV
goes
outside the range
[
SP
+
AL1H
-
HAL1
÷
SP
+
AL1L
+
HAL1
].
LHAb
OUT
AL1
AL1L
PV
HAL1
AL1H
-AL1L
AL1H
SP
HAL1
time
LHde
off
off
off
OUT
AL1
PV
time
off
off
off
ON
ON
ON
ON
HAL1
HAL1
Ab1
- Alarm configuration
This parameter can assume a value between
0
and
64
.
The number to be set, which will correspond to the function
desired, is obtained by adding the values reported in the fol-
lowing descriptions:
Alarm behaviour at power ON
the alarm output may behave in 2 different ways, depending
on the value added to parameter
Ab1
.
+0
Normal behaviour: The alarm is always activated when
there are alarm conditions.
+1
Alarm not activated at Power ON: If, at power ON, the
instrument is in alarm condition, the alarm is not activated.
The alarm will be activated only when the Process Palue,
after Power ON, has not been brought into the non-alarm
conditions and subsequently in the alarm conditions.
AL1
PV
time
off
off
Ab1 = +1
Ab1 = +0
off
off
ON
ON
ON
Example with absolute low alarm.
Alarm delay
The alarm output may behave in 2 different ways depending
on the value added to parameter
Ab1
.
+0
Alarm not delayed: The alarm is immediately activated
when the alarm condition occurs.
+2
Alarm delayed: When the alarm condition occurs, delay
counting begins, as programmed at parameter
AL1d
(expressed in seconds) and the alarm will be activated
