Operation and Configuration
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In the device with analog output the parameter CP has no influence on the control pro-
cess. The parameter CP is usually optimised during the autotuning (see 7.3).
In the ideal case, the output pulse period should coincide with the input polling period.
When a thyristor output is used, it is recommended to set the CP parameter to 1...2 s.
When a relay output is used, the life cycle of the contacts can be extended by increasing
the output pulse period, yet it can impair the control performance.
6.13
Signal retransmission
Linear signal 4-20 mA or 0-10 V can be scaled and transmitted to the analog output.
Configurable parameters for outputs of type U, I:
An-L
– Retransmission lower limit
An-H
– Retransmission upper limit
a) An-L < An-H
b) An-L > An-H
Fig. 6.11 Retransmission
The parameters
An-L
and
An-H
can be set in measuring units and are only for analog
output available. The valid range for
An-L
and
An-H
is limited by the measuring range for
temperature sensors or by
in-L
,
in-H
parameters for linear signals. The setting
An-L
=
An-H
is not allowed.
6.14
Alarm
There are two alarm functions: Range Alarm and Loop Break Alarm (LBA). Both alarm
functions can control digital output 2. If the alarm occurs, the respective LED (
А
LR
or
L
ВА
) flashes on.
6.14.1
Range Alarm
The alarm is activated when the process value is out of valid range. The following param-
eters should be set:
ALt
– Alarm Mode: one of the 11 standard alarm comparator schemes (Table.
6.4) can be selected
AL-d
– Alarm Threshold
AL-H
– Alarm Hysteresis
In case the initial
Pv
is definitely less than
SP
it is reasonable to use First Alarm Blocking
function that prevents the alarm activation at startup. Select the schemes 5…7, 10, 11 to
use the function.
Retransmission
lower limit
An-L
Retransmission
upper limit
An-H
I =4 mA
I =20 mA
min
max
12 mA
I
Retransmission
lower limit
An-L
Retransmission
upper limit
An-H
T
