请教高手： 本人因为工作需要，正在阅读611的资料，请问Tachometer adjustment是派什么用途的?
本人对于Feed modules,Resolver control中关于Tachometer　adjustment的下述一句话不够理解，：
The actual drive speed can,for a +/-10V speed setpoint,be varied within the following around the rated speed set as described under section 1.2;

　The rated speeds,set accoding to Section 1.2 result in the following setting ranges for a +/-10V speed setpoint