Lake Shore Model 340 Temperature Controller User’s Manual
Temperature Control Operation
6-1
CHAPTER 6
TEMPERATURE CONTROL OPERATION
6.0 GENERAL
There are many steps involved in setting up and operating a control loop. The earlier chapters of this manual
discuss hardware setup and the basic principals of tuning the control parameters to an individual system. This
section describes operation of the instrument control features and how to set control parameters. There are
several parameters that must be set before the Model 340 can perform even simple temperature control
functions. Each of the parameters in this chapter should be considered before turning the heater on. The user
should also verify that the sensor inputs are reporting correct temperature readings before proceeding.
The Model 340 has the ability to run two independent control loops, so it is called a two-loop controller.
Loop 1 is the primary control loop, capable of sourcing more power and has additional software features. The
heater output for Loop 1 is a traditional control output for a cryogenic temperature controller. Heater output is
the most visible difference between the two control loops which are summarized in Table 1-1. Loop 2 is an
auxiliary control loop with enough features to control a radiation shield or small sample heater. Setting up
hardware for the two control loops is discussed in Chapter 2. This section describes how to display control
loop parameters and output or make parameter changes.
Control loop display is described in Paragraph 6.1. Control loop enable is described in Paragraph 6.2. Control
loop filter is described in Paragraph 6.3. The control channel is described in Paragraph 6.4. Control modes
are described in Paragraph 6.5. Manual setting of PID control parameters are described in Paragraph 6.6.
Selecting an AutoTune control mode is described in Paragraph 6.7. Zone control data entry is described in
Paragraph 6.8. Using an open loop control is described in Paragraph 6.9. Setting a setpoint and setpoint units
are described in Paragraph 6.10. Setpoint ramping is described in Paragraph 6.11. Control output is
described in Paragraph 6.12. Finally, control output limits are described in Paragraph 6.13.
6.1 CONTROL LOOP DISPLAYS
This paragraph describes how the control parameters and control output are shown on the normal front panel
display. Control loops on the normal display are described in Paragraph 6.1.1. Loop indication on the normal
display is described in Paragraph 6.1.2. Loop indication on setting screens is described in Paragraph 6.1.3.
Finally, control output display is described in Paragraph 6.1.4.
6.1.1 Control Loops on the Normal Display
Several control parameters are shown on the normal display so they can be changed quickly by the operator.
The
CONTROL DISPLAY FORMAT
screen configures the control parameter portion of the display. The user
can decide to show parameters from one or both loops depending on the experiment. When one loop is in
operation, only that loop should be selected since more parameters are shown for that loop. When two loops
are shown, the operator must tell the instrument which loop to use before a parameter can be changed. Use
the
Display Format
key to get to the
CONTROL DISPLAY FORMAT
screen.
6.1.2 Loop Indication on the Normal Display
When operating both control loops, indicate which control loop changes by using the
Loop 1
and
Loop 2
keys. The key functions are not dependent on the display format, but the setting will default to the loop
showing on the display when only one loop is present.
The
Loop 1
key displays Loop 1 information. The
Loop 2
key displays Loop 2 information. The lower three
lines on either display show Loop parameters accessed from the normal display. Parameters unavailable for
Loop 2 do not display. After a time-out period the display returns to normal.
6.1.3 Loop Indication on Setting Screens
The loop indicator appears in the top left hand corner of setting screens; change it like a parameter for that
screen. Press
Enter
after selecting a loop to display parameters for that loop on the setting screen.