Input Mode For Analog Output; Example Of Low And High Parameter Setting; Loop 2 Mode For Analog Output 2 - Lakeshore 340 User Manual

7.1.1

Input Mode for Analog Output

When input mode is
chosen for an analog
output, there are several
other parameters to set.
The sensor input must
be chosen and the data
source from the input.
Sensor input setup
including operation of
the linear equation is
discussed in Paragraph
5.3.3.
Once the sensor input
data is directed to an analog output, there are two other parameters that must be set. The low and high
parameters define the 6-digit sensor input reading values that comprise the bottom and top of the analog
output voltage range. The scale factor can be selected as n, u, m, k, M, or G. Blank indicates a scale factory
of x1. These parameters are included so the user can control the range and sensitivity of the output. The
example below demonstrates how the high and low parameters work.
To configure an analog output, select the Mode and Bipolar setting, then continue with the other parameters
listed above. Highlight the parameter field and select the appropriate setting values. Press the Save Screen
key when finished to save the changes. The Value % field that appears is not a settable parameter in this
mode. It reports the analog output status in percent of full scale.
7.1.2

Example of Low and High Parameter Setting

With the analog output set
to linear mode, the
temperature input data
and voltage output data
are related as shown:
The first figure results in a
wide temperature range
but sensitivity is poor. The
resulting sensitivity is
0.01 V/K or 10 mV/K.
If the application does not require a wide temperature range, the user can change the value of the low and
high parameters to improve sensitivity. This setup has a narrow range with much improved sensitivity of
0.2 V/K or 200 mV/K. Please note that in any application, the resolution of the analog output voltage is
always 1.25 mV as specified.
The second figure shows how sensitivity improves when working at liquid nitrogen temperature (77 K).
7.1.3

Loop 2 Mode for Analog Output 2

Discussion about using Analog Output 2 as the control output for Loop 2 is contained in the control operation
chapter. Loop 2 must be chosen as the mode for analog output 2 and the bipolar setting should match the
capability of the control system. It is recommended to set the Analog Output to unipolar mode. Few
applications can use bipolar control output. A thermo-electric cooling element is one example of a control
actuator that can utilize a bipolar control output.
7-2
Lake Shore Model 340 Temperature Controller User's Manual
Input Sensor Input used for input reading data. The default setting is A.
Source Source of data from the input. The default is Temp K.
Temp K
Temp C
Sensor
Linear
Low Reading data value that corresponds to -10 V when bipolar, 0 V
when unipolar. The value may be set as a six digit floating point
number. The default setting is 0.
High Reading data value that corresponds to +10 V. The value may be set
as a six digit floating point number. The default setting is 1000.
Input A Temperature (K)
Unipolar Output (V)
Input A Temperature (K)
Unipolar Output (V)
Kelvin temperature reading from an input.
Celsius temperature reading from an input.
Sensor units reading from an input.
Linear equation data from an input.
Low
0
|---------|---------|---------|---------|---------|---------|
0
Low
50
|---------|---------|---------|---------|---------|---------|
0
Analog, Digital, Alarm & Relay Operation
High
500 1000
+5 +10
High
75 100
+5 +10