Thermo Scientific Neslab Merlin M 75, Manual

Page: 80 / 107

2 - 10 Merlin
Chapter 2
Thermo Scientific
The Setup/Tuning Loop, see illustration next page, is used to configure the
controller temperature display and various operating parameters. To enter the
loop you must be displaying the reservoir fluid temperature and then, while
pressing and holding , press . The display indicates . Use the
arrow keys to enter/bypass the loop. Once in the loop press to sequence
through it. Use the arrow keys to change any display.
The loop is used to determine how the chiller reacts when a fault occurs
— either shut down or continue to run . The chiller is shipped
configured to run.
It is also used to configure the temperature displays to indicate to a tenth of a
degree .
The loop is used to select which temperature sensor the high and low
temperature monitors uses . is the internal sensor, is
the optional external sensor. is available only if the external sensor is
properly connected to the rear of the chiller.
If the optional remote probe is enabled, the loop is used to set the remote
probe temperature deviation limit. This limit is applied to the setpoint
to calculate the minimum fluid temperature supplied to your application. For
example, if the setpoint is 10°C and the deviation is set to 3°C, the coldest
fluid temperature supplied to your application is limited to 7°C.
The deviation can be set from 1°C to 53°C. The factory default setting is 50°C.
The loop can also be used to set the controller's PID parameters. The factory
preset values are in Chapter 4.
Thermo Fisher recommends that only a qualified technician change PID
parameters. Incorrect PID values will hamper chiller performance.

The heat PID is only applicable to chillers configured with a heater.
The loop is also used to adjust/verify serial communication parameters
. This section of the loop is applicable only to chillers configured for
serial communications capability.
Changes made in the Tuning/Setup Loop take affect when is pressed at
the prompt. Pressing at the prompt aborts all changes.
Setup/Tuning Loop
CAUTION