# Normalisation of the velocity

Example 1:

The drive expects 10E-4 revolutions/minute at the velocity interface (SERCOS preferred scaling).

v_time_base = 0       // [minutes]

v_reso_num = 10000    // [increments]

v_reso_denom = 360000 // [0.001 °]

Example 2:

The drive expects mm/minute at the velocity interface.

v_time_base = 0       // [minutes]

v_reso_num = 1        // [increments]

v_reso_denom = 1000   // [1 μm]

Example:

The settings of SECOS parameters S-0-0044, S-0-0045 and S-0-0046 and an existing gear must be considered to determine the velocity scaling of a SERCOS spindle. As an example, the drive should use the following scaling:

Velocity data scaling S-0-0044 = 00000000 00001010

Velocity data scaling factor S-0-0045 = 55880

Velocity data scaling exponent S-0-0046 = -9

The velocity scaling S-0-0044 is therefore rotational referred to revolutions/minute. As a result, with a 1 increment in the velocity interface S-0-0040 the drive rotates at

v = S-0-0045 * 10^(S-0-0046) rpm = 55880*10^-9 rpm

when referred to 10^-3° this is

v = 55880 * 360000 * 10^-9 * 10^-3°/min = 20,1168 * 10^-3°/min

In addition, the spindle has a gear which has a ration of 1 : 2. This must also be considered to determine the velocity resolution. If the drive rotates at v = 20,1168 * 10^-3°/min (1 velocity increment), the CNC axis moves due to the gear ratio of 1: 2 at v_CNC = 2 * 20,1168 * 10^-3°/min = 40,2336 * 10^-3°/min.

This value results in the 3 parameters for velocity resolution:

antr.v_time_base = 0      (time base: minutes)

antr.v_reso_num = 10000   (velocity increments)

antr.v_rso_denom = 402336 (per 10^-3°)