Parr Instrument 4857 User Manual
Page 18
4857 Reactor Controllers
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O
PERATION OF THE
4857
P
ROCESS
C
ONTROLLER
(
CONTINUED
)
Autotuning
The 4857 Process Controller is equipped with default PID values from the factory designed to
give reasonable temperature control across a wide temperature range. Autotuning is not
recommended unless the system has exhibited poor control using the default PID values.
The 4857 Process Controller may be auto tuned at setpoint. Using the other types of auto tune
(not the tune at setpoint) will likely result in an error.
1. Bring the system to the desired setpoint for the process by adjusting the setpoint of the
controller. Let the system come to equilibrium and hold steady at the setpoint for at least ten
minutes. This step may require that the temperature overshoot or undershoot significantly
with existing PID values.
2. Right click on the main screen, select "Properties >> Module 1", and then change the mode
on "Autotune Setting" to "ATSP".
3. On the main screen, Module 1 should flash “ATSP" at the bottom. This indicates that the
controller is tuning.
4. During the auto tune, the temperature may rise or fall by a few degrees. This is normal.
When the auto tune is complete, the “ATSP" will stop flashing. The temperature should
remain at the setpoint upon completion of the auto tune.
5. Check the PID settings in Module 1 after the autotune. Values which were changed by the
auto tune will have an “A” before the value.
6. If the auto tune selected a value of less than 5 for either the CyC.t or CyC.2, change this
value back to 5. If it selected a value larger than 5, this is OK.