The Direct Calibration button opens a window for keyboard
entry of values, which are then compared with measured voltages to produce
a conversion equation by linear regression, power function, or
2order polynomial. The window shows the entered points, the regression
line and regression coefficient, and the conversion equation. At least
three points must be entered before a valid conversion is generated.
For each point, sent the instrument in question to a particular value, enter
that value in the edit field, and click the 'get voltage' button
(or hit return). Repeat as necessary with different instrument values.
Note that negative inputs (values or voltages) are not accepted when using
power functions. A display of the regression residuals is shown when
the residuals button is clicked. Here is an example (a 2order
polynomial conversion is selected).
When done, click the 'Conversion OK'
button.
 Note that although entering voltage conversion equations can be tedious,
particularly for multichannel sampling protocols, you can save conversions
in 'setup' files for immediate retrieval and reuse.
