Rockwell Automation 1746-HSRV SLC Servo Control Module User Manual - Manual (Page 93)

Publication 1746-6.1.2 - July 2000
7-14 Setting Up Your SLC Servo Module
To enter encoder lines:
1. Refer to the encoder manufacturer’s specification for the
encoder lines.
2. Enter the value of the Encoder Lines parameter in configuration
file F8 (words 4-5).
3. Enter the value of the Counts Per Position Unit parameter in
configuration file F8 (words 6 and 7).
Computing Counts Per Position Unit
Use the following equation to calculate the value of the Counts Per
Position Unit parameter as it is used in step 3 above.
1 Where the revs/position unit contains gearing and the pitch of the ball-screw.
In the example below, an axis uses a 1000 line encoder in a motor
coupled with a 3:1 reducing gear to a 5 pitch lead screw (5 turns per
inch). With a position unit of inch, the value of the Counts Per
Position Unit parameter is computed as:
Computing Maximum Speed Scaler
Speed scaler refers to the varying of incoming voltage to produce a
varying speed. To compute a variable output speed, the SLC Servo
Module uses the number of pulses from the encoder, the maximum
motor rpms, and speed that you want.
For reliable axis operation, the axis speed you want must be less than
the digital analog convertor (DAC) saturation speed. The DAC
saturation speed must be less than the motor operation speed at low
Counts per position
unit is equal to: Multiplied by the: Multiplied by the:
4 Number of encoder lines Revs/position unit 1
Lines per
revolution: Multiplied by
counts per line: Multiplied by
input
revolutions/
output
revolutions: Revolutions per
inch: Equals counts
per inch:
1000 4 3 5 60000