Delta Tau GEO BRICK LV Manuel D’Utilisation
Turbo PMAC User Manual
60
Setting Up Feedback and Master Position Sensors
High-Resolution (x4096) Interpolators
For the high-resolution interpolators, the interpolation algorithm produces data with the LSB representing
1/4096 of an encoder line. Since the Turbo PMAC motor software considers this data to be in units of
1/32 of a count, this means that the software considers there to be 128 counts per encoder line. Other
motor and axis position, velocity, and acceleration values are based on this definition of a count which we
will call a software count.
1/4096 of an encoder line. Since the Turbo PMAC motor software considers this data to be in units of
1/32 of a count, this means that the software considers there to be 128 counts per encoder line. Other
motor and axis position, velocity, and acceleration values are based on this definition of a count which we
will call a software count.
Note that the hardware counter in the Servo IC of the high-resolution interpolator only contains four
counts per line of the encoder. If using the encoder for Turbo PMAC-based commutation, use the
hardware counter register as the commutation position source, not the interpolated result, and this
hardware count resolution should be known.
counts per line of the encoder. If using the encoder for Turbo PMAC-based commutation, use the
hardware counter register as the commutation position source, not the interpolated result, and this
hardware count resolution should be known.
Low-Resolution (x128/x256) Interpolators
For the low-resolution interpolators, the interpolation algorithm produces data with the LSB representing
1/128 or 1/256 of an encoder line, and the hardware counter for the channel has data with the LSB
representing 1/4 or 1/8 of an encoder line, depending on the setting of the resolution jumper for the
interpolator. Since the Turbo PMAC motor software considers this data to be in units of 1/32 of a count,
the software considers there to be four or eight counts per encoder line, matching the resolution of the
encoder counter. However, compared to 1/T timer-based sub-count estimation, this method produces real
fractional-count position data (i.e. command and hold final position to resolution less than a count).
1/128 or 1/256 of an encoder line, and the hardware counter for the channel has data with the LSB
representing 1/4 or 1/8 of an encoder line, depending on the setting of the resolution jumper for the
interpolator. Since the Turbo PMAC motor software considers this data to be in units of 1/32 of a count,
the software considers there to be four or eight counts per encoder line, matching the resolution of the
encoder counter. However, compared to 1/T timer-based sub-count estimation, this method produces real
fractional-count position data (i.e. command and hold final position to resolution less than a count).
Setting up Resolvers
A Turbo PMAC system can interface directly to resolvers through an Acc-8D Option 7 resolver-to-digital
(R/D) converter board. This board can create the AC excitation signal for up to four resolvers, accept the
modulated sine and cosine signals back from these resolvers, demodulate the signals and derive the
position of the resolver from the resulting information, in an absolute sense if necessary.
(R/D) converter board. This board can create the AC excitation signal for up to four resolvers, accept the
modulated sine and cosine signals back from these resolvers, demodulate the signals and derive the
position of the resolver from the resulting information, in an absolute sense if necessary.
Note:
Many Turbo PMAC users will utilize resolvers for position feedback, but with the
resolver-to-digital conversion performed in the servo amplifier, which uses the
resulting position information for its commutation functions. This style of
amplifier generates a synthesized digital quadrature signal for the controller, which
is connected to the Turbo PMAC. In this case, the Turbo PMAC treats the
feedback just as if a real digital quadrature encoder were used.
resolver-to-digital conversion performed in the servo amplifier, which uses the
resulting position information for its commutation functions. This style of
amplifier generates a synthesized digital quadrature signal for the controller, which
is connected to the Turbo PMAC. In this case, the Turbo PMAC treats the
feedback just as if a real digital quadrature encoder were used.
Hardware Setup
The details of the hardware setup are covered in the hardware reference manual for the R/D converter
board. Fundamentally, the R/D board connects three differential analog signal pairs to each resolver: a
single excitation signal pair, and two feedback signal pairs. It has two different digital connections to the
Turbo PMAC: one for serial absolute position to the JTHW Multiplexer port (common for all channels on
the board, optional in use), and one with synthesized digital quadrature for each channel, connected to a
normal quadrature encoder interface.
board. Fundamentally, the R/D board connects three differential analog signal pairs to each resolver: a
single excitation signal pair, and two feedback signal pairs. It has two different digital connections to the
Turbo PMAC: one for serial absolute position to the JTHW Multiplexer port (common for all channels on
the board, optional in use), and one with synthesized digital quadrature for each channel, connected to a
normal quadrature encoder interface.
Turbo PMAC Hardware-Control Parameter Setup
Encoder Decode Control: I7mn0, I68n0, MI910
To match the resolution and direction sense of the ongoing position information derived from the
synthesized quadrature with absolute position read through the Multiplexer port, set the channel’s encoder
decode variable to 7 (times-4 decode, counterclockwise). If not using absolute position, set the decode
resolution and direction as wanted. For Servo ICs of both PMAC-style and PMAC2-style, this is I7mn0
(for Servo IC m Channel n). For MACRO IC 0 Channel n* on a Turbo PMAC (a handwheel port
encoder), this is I68n0. For encoder channels on a MACRO Station, this is node-specific variable MI910.
synthesized quadrature with absolute position read through the Multiplexer port, set the channel’s encoder
decode variable to 7 (times-4 decode, counterclockwise). If not using absolute position, set the decode
resolution and direction as wanted. For Servo ICs of both PMAC-style and PMAC2-style, this is I7mn0
(for Servo IC m Channel n). For MACRO IC 0 Channel n* on a Turbo PMAC (a handwheel port
encoder), this is I68n0. For encoder channels on a MACRO Station, this is node-specific variable MI910.