Delta Tau GEO BRICK DRIVE Manuale Utente
Geo Brick Drive User Manual
Pinouts and Software Setup
107
Setting up SSI | EnDat | BiSS
In Turbo PMAC (i.e. Brick family), the absolute serial encoder data is brought in as an unfiltered parallel
Y-word into the Encoder Conversion Table (ECT) where it is processed for the PMAC to use for on-
going position in the motor servo-loop, power-on absolute position, and (power-on/on-going) phase
referencing. In general, encoder data is left-shifted 5 bits in the ECT to provide fractional data. This
process can cause saturation of certain registers with higher resolution absolute serial encoders, thus for
this type of encoders, it is recommended to process the data as unshifted. Moreover, special
considerations need to be taken in setting up commutation (for commutated motors, e.g. brushless).
Y-word into the Encoder Conversion Table (ECT) where it is processed for the PMAC to use for on-
going position in the motor servo-loop, power-on absolute position, and (power-on/on-going) phase
referencing. In general, encoder data is left-shifted 5 bits in the ECT to provide fractional data. This
process can cause saturation of certain registers with higher resolution absolute serial encoders, thus for
this type of encoders, it is recommended to process the data as unshifted. Moreover, special
considerations need to be taken in setting up commutation (for commutated motors, e.g. brushless).
Note
Details about registers’ overflow and examples can be found in the
appendix section.
appendix section.
The following flowchart summarizes the recommended method to use, regardless of the Multiturn (MT)
data specification. It is only dependent on the Singleturn (ST) resolution (for rotary encoders) or protocol
resolution (for linear scales).
ST
Encoder Resolution
≥ 24 bits
NO
YES
ST
Encoder Resolution
≥ 19 bits
NO
YES
Technique 2
Technique 1
Technique 3
Start Here
Technique 1
This technique places the Least Significant Bit (LSB) of the serial data in bit 5 of the result register
providing the 5 bits of “non-existent” fraction.
providing the 5 bits of “non-existent” fraction.
Technique 2
This technique places the LSB of the serial data in bit 0 of the result register, creating no fractional bits. It
requires a dedicated Encoder Conversion Table (ECT) entry for commutation.
requires a dedicated Encoder Conversion Table (ECT) entry for commutation.
Technique 3
This technique processes the data for position similarly to Technique 1, but it requires a dedicated ECT
entry for commutation.
entry for commutation.
Note
Some applications may require deviating from the suggested setup
methods (e.g. extremely high resolution and speed requirements).
Contact Delta Tau for assistance with these special cases.
methods (e.g. extremely high resolution and speed requirements).
Contact Delta Tau for assistance with these special cases.