Emerson FM-3 manual Decimal Places, Scaling, Characteristic Distance, Characteristic Length

Setting Up Parameters

Decimal Places

The number of decimal places set in this parameter determines the number of digits after the decimal point used in all distance and position parameters throughout the software. Using a high number of decimal places will improve position resolution, but will also limit the range of absolute position. You can select from zero to six decimal places of accuracy.

Note

When the number of decimal places are changed in an existing configuration file the Index accel and decel parameters need to be checked.

Scaling

A Characteristic Distance and Length must be established to allow the FM-3 module to scale user units back to actual motor revolutions. This scaling factor is as follows:

Characteristic Distance

Scaling = -------------------------------------------------------

Characteristic Length

Characteristic Distance

This is the distance the load travels (in user units) when the motor travels the characteristic length (in motor revolutions).

Characteristic Length

This is the distance the motor travels (in whole number of revolutions) to achieve one characteristic distance of load travel.

Distance Scaling Examples:

A 1.5" diameter pulley is used to drive a conveyor belt, and the user wishes to use units of inches instead of revolutions.

Units Name — Set to Inches

Decimal Places — Set to desired accuracy 0.000

In one revolution of the motor (or pulley), the belt will travel a distance of one pulley circumference.

=1.5" x π

=1.5 x 3.14...

=4.712 inches / revolution

Characteristic Distance = 4.712

Scaling = ---------------------------------------------------------------------------

Characteristic Length = 1

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