The LabVIEW SoftMotion Module (no longer sold by NI) was an add-on for LabVIEW that helped with the control of motors and drives using high-level commands and develop custom motion applications using NI real-time and FPGA.
The SoftMotion Drive Interface (SDI) is the solution NI developed to standardize communication with third-party EtherCAT motor drives. Conventional communication with an EtherCAT-capable motor drive is done by reading and writing commands to PDO and SDO memory registers on a drive. The SDI takes care of this low-level communication to PDO and SDO registers for you, and allows you to focus on the high-level control aspects of your application using the SoftMotion API. SDI Plug-ins contain all the necessary components to add the EtherCAT drive to your LabVIEW Project and control the drive using SoftMotion.