5.3. A
CQUISITION OF RESPONSES
. The keyboard is disabled throughout the whole acquisition phase, while
and the measured
temperature value appear alternately on the display. If there is a power failure during this phase, the next time the instrument is
switched on, after the initial internal self-test phase, it continues the auto-tuning function. To manually abort the auto-tuning function
without modifying the control parameters, keep button
pressed for 3 seconds.
Upon successful completion of auto-tuning, the controller updates the value of the control parameters and starts to control.
5.4. E
RRORS
. If the auto-tuning procedure is unsuccessful, an indication of the error that has caused the failure blinks on the display:
timeout error 1: the controller has not succeeded in bringing the system temperature within the proportional band.
Temporarily increase the set point with control in the heating mode and vice versa in the cooling mode, then restart the
procedure.
timeout error 2: the auto-tuning procedure has not finished within the maximum set time (1000 cycle times). Restart the auto-
tuning procedure and set a higher cycle time.
temperature over range: after having checked that the error has not been caused by a sensor malfunction, temporarily
decrease the set point with control in the heating mode and vice versa in the cooling mode and then restart the procedure.
To erase the error indication and return to the normal mode, press the key
.
5.5. C
ONTROL IMPROVEMENT
. If the resulting control is unsatisfactory, proceed as follows:
to reduce overshoot, decrease the integral action reset
1Ar
;
to increase the response speed of the system, decrease the proportional band
1Pb
; caution: doing this makes the system less stable;
to reduce swings in steady-state temperature, increase the integral action time
1It
; system stability is thus increased, although
its response speed is decreased;
to increase the speed of response to the variations in temperature, increase the derivative action time
1Dt
; caution: a high value
makes the system sensitive to small variations and may be a source of instability.
CAUTION
: during the auto-tuning procedure the temperature oscillates near the set point; it is therefore advisable to remove
products to be controlled within severe specifications
6. RECALIBRATION
If it is necessary to recalibrate the instrument, for example following replacement of a sensor, proceed as follows: have a precision
reference thermometer or a calibrator to hand; ensure that the offset
OS1
and the simulation
SIM
are set to 00. Switch the
controller off then on again. During the internal self-test phase, press the keys
+
and keep them pressed till the auto-test phase
is over. With the recalibration function activated, select the value to be changed using
or
:
0Ad
allows a calibration of 0,
inserting a constant correction over the whole scale of measurement.
SAd
allows a calibration of the top part of the measurement
scale with a proportional correction between the calibration point and 0. After having selected the required parameter, press
to display the value and use +
or
to make the read value coincide with the value measured by the reference instrument
(ensure that the temperature is stable). Exit from calibration by pressing the key
.
7. SERIAL COMMUNICATION
LTR15 is provided with a serial port for connection with a PC or a programmer. In the first case it is important to assign a different
value to the
ADR
parameter for each linked unit (peripheral address); in the case of automatic programming, ADR should remain
at 1.
WARRANTY
LAE electronic SPA guarantees its products against defects due to faulty materials or workmanship for one (1) year from the date of manufacture shown on the container. The Company shall
only replace products which are shown to be defective to the satisfaction of its own technical services. The Company shall not be under any liability and gives no warranty in the event of
defects due to exceptional conditions of use, misuse or tampering.
LAE electronic does not accept units back unless LAE electronic has previously given its allowance or request.
INSTRUCTIONS FOR INSTALLATION AND USE.