Another issue could be that an encoder is a speed feedback device and is not the best suited feedback device for holding. Velocity feedback is a pure integration function and position is not so the problem may be related to the type of feedback relative to the application...Something to think about
PLEASE SEE THE ATTACHED LINK TO THE SIEMENS mANUAL DOWNLOAD SITE. tHIS SHOULD TAKE YOU RIGHT TO THE PAGE FOR THIS CARD. i HOPE THAT THIS IS OF SOME HELP...