Lakeshore 325, Руководство пользователя, Страница: 61 / 166

Lake Shore Model 325 Temperature Controller User’s Manual
Operation 4-13
Filter (Continued)
Use the
s
or
t
key to toggle between Filter On and Off. If you select Off, the routine will end and return you to the
normal display. If you select On, the routine will continue with the following.
Select for InputA °®
Filter Points 08
Use the
s
or
t
key to increment or decrement the Filter Points from 02 through 64, with 08 being the default. Press the
Enter key. You will see the following display.
Select for InputA °®
Filter Window 01%
Use the
s
or
t
key to increment or decrement the Filter Window from 01% through 10%, with 01% being the default.
Press the Enter key. You will return to the normal display.
4.6 TEMPERATURE CONTROL
There are many steps involved in setting up a temperature control loop. Chapter 2 of this manual describes the principals
of closed loop (feedback) control. Chapter 3 describes necessary hardware installation. The following sections of this
chapter describe how to operate the control features and set control parameters. Each control parameter should be
considered before enabling a control loop or the instrument may not be able to perform the most simple control
functions. A good starting point is deciding which control loop to use, whether to operate in open or closed control mode
and which tuning mode is best for the application. Other parameters fall into place once these have been chosen.
4.6.1 Control Loops
The Model 325 is capable of running two simultaneous control loops. Their capabilities are compared in Table 4-3. As
shown there the primary difference between the two loops is their control output.
Loop 1: Loop 1, the primary control loop, is the traditional control loop for a cryogenic temperature controller. It
includes the largest set of hardware and software features making it very flexible and easy to use. Loop 1 uses the
heater output as its control output. The heater output is a well-regulated 25 W DC output with two power ranges. This
provides quiet, stable control for a broad range of temperature control systems in a fully integrated package.
Loop 2: Loop 2, the auxiliary control loop, shares most of the operational features of loop 1 but uses the 2W, 10 V
output as its control output. By itself, Loop 2 is capable of driving a sample heater or other low power load. It is also
suited to drive the programming input of a voltage programmable power supply. In combination the controller and
supply can be used to control large loads at high temperatures.
The keypad and display operate on one loop at a time. To toggle display and keypad operation between Loop 1 and
Loop 2 press the
Loop key. A brief display message indicates which control loop has been selected. You can determine
which loop is active by looking at the heater output display. Loop 1 has “Low” or “High” in the heater display. Loop 2
has “L2” in the heater display. Also, when you select any of the following parameters, the active loop number will be
displayed: Control Setup, Setpoint, P, I, D, Manual Heater, Zone Settings, AutoTune, and Heater Range.