Lake Shore Model 370 AC Resistance Bridge User’s Manual
Max/Min Capture (Continued)
To reset the Max/Min feature press the
Max/Min
key twice. The following message appears as a prompt after the key is
pressed the first time. Captured values for all inputs will be reset at the same time.
Press Max/Min To Reset
Enter To Continue.
4.13 LINEAR EQUATION (
Δ
R)
The Model 370 can scale one source of reading data from each channel with either of two linear equations. Scaled
readings can be displayed or sent to the analog voltage output as a control signal. The feature can be configured to
calculate an error value,
Δ
R, or a scaled error value such as 10
Δ
R.
The two equations, MX+B and M(X+B), have subtle differences. The first equation is most often used to scale a sensor
reading that has a linear response but requires offset and gain correction. The second can easily produce a scaled error
value when the control setpoint is used for B. A summary of parameter selections is listed as follows:
Equation
M
X
B
MX+B
M(X+B)
Value
Ohms
Kelvin
Value
+SP
–SP
where M = Slope of line, X = Reading data, B = Offset of line, Value = Number value entered by user, and
SP = Temperature control setpoint value.
The instrument will calculate meaningless numbers if this feature is not configured properly. For example, the setpoint
units and reading units for X must match if SP is used in the equation. The display resolution can also be misleading. For
example, the scaled error value of 10
Δ
R does offer more measurement resolution than the normal display reading.
However, increasing the slope, M, to 100 or 1000 will only increase the display resolution and not the measurement
resolution.
To begin linear equation setup press the
Linear (
Δ
R)
key. If a scanner is installed, the first filter setup screen appears as
a prompt for the channel number for X. All of the parameter changes that follow will act on the selected channel. If no
scanner is installed, the sequence will begin below with equation selection.
Linear Setup
Select With °®
Channel: 1
Use the
s
or
t
key to select a channel number between 1 and 16. Choose the selection “All” and the changes will be
applied to all channels at the same time. Press
Enter
to accept the new selection and continue to the next setting screen.
Press
Escape
to cancel the new selection and return to the normal display.
The next linear setup screen appears as a prompt for the equation.
Linear Setup
Channel 1
Select With °®
Equation: M(X+B)
Use the
s
or
t
key to select M(X+B) or MX+B. Press
Enter
to accept the new selection and continue to the next
setting screen. Press
Escape
to cancel the new selection and return to the normal display.
4-24
Operation
