Calibration Bath
Digital Communication Interface
49
Read Expansion Valve 1
f3
f3
f3:9
f3:1
Set Expansion Valve 1
f3=1/0
0 or 1
Set Expansion Valve 1 to on
f3=n
f3=1
Set Expansion Valve 1 to off
f3=n
f3=0
Read Cooling Power
f4
f4
f4:9
f4:1
Set Back Pressure
f4=1/0
0 or 1
Set back pressure on
f4=n
f4=1
Set back pressure off
f4=n
f4=0
Legend: [ ] Optional Command data
{ } Returns either information
n Numeric data supplied by user
9
Numeric data returned to user
x Character data returned to user
Note:
When DUPLEX is set to FULL and a command is sent to READ, the command is returned followed by a carriage return and linefeed. Then the value is returned as indicated in the RETURNED
column.
Power Control Functions
The digital interface is capable of controlling the heating and cooling functions so
that the bath can be remotely operated at any temperature within the range of the
bath. To allow the interface to control the heating and the cooling, the front panel
controls are disabled by 1) switching the heater switch to LOW, and 2) switching
the refrigeration switch to OFF. Otherwise, the interface would not be able to
switch these functions off. The bath has four control functions with the digital
interface. These are heater power high/low, cooling on/off, expansion valve
open/closed, and back pressure valve open/closed.
Heater Control
To control the heater with the digital interface the front panel heater switch must
be set to LOW (500 W). The heater function is controlled with the “F1" command.
Setting the “F1" parameter to 0 sets the heater to LOW (500 W) and setting it to 1
sets the heater to HIGH (1000 W). Sending “F1" with no value causes the
controller to return a value showing what the heater setting is. When the heater
setting is changed a pop is heard as the heater relay opens or closes.