beled “HIGH” controls the cooling temperature when the expansion valve is
open or on. This should be adjusted for approximately 45–50 psi. These values
are typical but may be adjusted as required for specific applications. The low
range must be set to a lower pressure (temperature) than the high range valve.
The “F4" command controls the back pressure valve. When the valve is open
the cooling capacity is significantly reduced. This valve should normally be left
off/closed throughout the operating range of the bath. Table 5 summarizes the
control functions for heating and cooling. Table 6 shows the recommended
control settings for each operating temperature range. The ranges may need to
be adjusted depending on the bath application.
57
10 Digital Communication Interface
Power Control Functions
Function
Command
0
1
Heater
F1
low
high
Refrigeration
F2
off
on
Expansion valve
F3
open
closed
Back pressure
F4
open
closed
Table 5
Serial Power Control Functions
Range
Heater
Refr.
Exp.
–10 to 15°C
low
on
open
15 to 40°C
low
on
closed
40 to 110°C
low/high
off
open
Table 6
Temperature Range Control Functions
