54
c
HAPTER
4:
Operation
Model 335 Temperature Controller
4.4.11 Preferred Units
The Preferred Units parameter setting determines which units are used to display
setpoint and max/min parameters whenever these parameters are displayed in any
display mode. The sensor reading is also displayed in Preferred Units in all display
modes except for the Custom display mode, where each sensor location can be
assigned specific display units.
Menu Navigation:
Input Setup
Q
Input
(
A
, or
B
)
Q
ENTER
Q
Preferred Units
(Kelvin, Celsius, or Sensor)
Interface:
INTYPE
4.4.12 Max/Min
The Max/Min feature captures and stores the highest (Max) and lowest (Min) reading
taken since the last reset. The Preferred Units parameter, under the Input Setup
menu, determines the units used for capturing Max and Min.
Max and Min are always being captured, so there is no need to turn the feature on or
off. The readings are reset when the instrument is turned on, sensor input parameters
are changed, or the
Max/Min Reset
key is pressed.
Menu Navigation:
Max/Min Reset
Interface:
MNMXRST
4.5 Output and
Control Setup
Once the sensor inputs have been configured (section 4.4), the outputs can be config-
ured. The Output Setup menu is used to create control loops for controlling tempera-
ture, whether using feedback (closed loop) or manually setting the output (open
loop). This section describes how to operate the output and control features, and how
to set control parameters. Each control parameter should be considered before turn-
ing on a control loop output 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.
Section 2.7 of this manual describes the principals of closed loop proportional, inte-
gral, and derivative (PID) control.
4.5.1 Heater Outputs
Heater Outputs 1 and 2 are traditional control loop heater outputs for a cryogenic
temperature controller. The two outputs are identical except in the amount of power
available. Output 1 can provide up to 75 W when Output 2 is configured as a voltage
output, or 50 W when Output 2 is configured as a current output. Output 2 can pro-
vide up to 25 W when configured as a current output, and 1 W when it is configured
as a voltage output.
The outputs include a large set of hardware and software features, making them very
flexible and easy to use. The current outputs are well-regulated DC outputs. This pro-
vides quiet, stable control for a broad range of temperature control systems in a fully
integrated package. The power ranges for each output provide decade steps in power.
Menu Navigation:
Output Setup
Q
Output
(1 or 2)
Default: Current
Interface:
HTRSET
