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SSI Encoder Evaluation

Valid for S300, S700 from FW 2.14

Parameter setup for SSI Encoder evaluation

A SSI encoder (absolute encoder) must be setup with these parameters:

  • SSIRXD  – number of SSI bits to read
  • SSIREVOL  – number of bits for multi-turn information
    These parameters are used to calculate the number of bits per encoder rotation = SSIRXD - SSIREVOL
  • SSIGRAY = 0 binary coded
                   =1 gray coded
  • ENCMODE=0 SSI interface used as input
  • SSITOUT = 0 1MHz SSI-Clock
                   = 1 500KHz SSI-Clock
                   = 2 250KHz SSI-Clock  (only ext. position feedback)
                   = 3 125KHz SSI-Clock  (only ext. position feedback)
  • SSIINV      = 0 SSI-Clock not inverted (see connection drawing)
                     = 1 SSI-Clock inverted 

All setting can done in the setup software or in a terminal program. Parameter overview see page Parameters for SSI Interface.

The SSI encoder can be used for

  1. primary feedback   FBTYPE=9
    with this setting the SSI encoder is configured as commutation feedback.
    Update rate 62,5 µ
  2. external position feedback EXTPOS=5
    with this setting the SSI encoder is configured as position feedback
    Update rate 125 µsec @ DPWM=3 (8 KHz position control)
                          250 µsec @ DPWM<>3 (default; 4 KHz position control)
    EGEARI, EGEARO sets the gearing ratio for the external gearing
  3. master information for MasterSlave operation GEARMODE=5
    Update rate 250 µsec
    GEARI, GEARO sets the gearing ratio for the master-gearing

The SSI data are stored in the varable CNTSSI, format refers to the value of SSIRXD and SSIREVOL.