Delta Tau GEO BRICK LV User Manual
Turbo PMAC User Manual
112
Setting Up Turbo PMAC-Based Commutation and/or Current Loop
Only the DAC_CLK signal is directly used with the sine-wave output, to control the frequency of the
serial data stream to the DACs. The default DAC clock frequency of 4.9152 MHz is suitable for the
DACs on all Delta Tau hardware. Refer to the I7m03 description for detailed information on setting these
variables.
serial data stream to the DACs. The default DAC clock frequency of 4.9152 MHz is suitable for the
DACs on all Delta Tau hardware. Refer to the I7m03 description for detailed information on setting these
variables.
The encoder SCLK frequency should be at least 20% greater than the maximum count (edge) rate that is
possible for the encoder on any axis. Higher SCLK frequencies than this minimum may be used, but
these make the digital delay anti-noise filter less effective.
possible for the encoder on any axis. Higher SCLK frequencies than this minimum may be used, but
these make the digital delay anti-noise filter less effective.
DAC Strobe Control: I7m05, MI905, MI909
Turbo PMAC generates a common DAC strobe word for each set of four machine interface channels. It
does this by shifting out a 24-bit word each phase cycle, one bit per DAC clock cycle, most significant bit
first. I7m05 (MS{anynode},MI905 or MS{anynode},MI909 on a MACRO Station) contains this
word for the channels on Servo IC m. The default value of $7FFFC0 is suitable for use with the 18-bit
DACs used with the PMAC2-style Servo ICs on Delta Tau interface and breakout boards. A value of
$7FFF00 is suitable for 16-bit DACs.
Turbo PMAC generates a common DAC strobe word for each set of four machine interface channels. It
does this by shifting out a 24-bit word each phase cycle, one bit per DAC clock cycle, most significant bit
first. I7m05 (MS{anynode},MI905 or MS{anynode},MI909 on a MACRO Station) contains this
word for the channels on Servo IC m. The default value of $7FFFC0 is suitable for use with the 18-bit
DACs used with the PMAC2-style Servo ICs on Delta Tau interface and breakout boards. A value of
$7FFF00 is suitable for 16-bit DACs.
Individual-Channel Hardware Setup
For each machine interface channel n (n = 1 to 4) of Servo IC m used for sine wave analog outputs, a few
I-variables must be set up properly.
I-variables must be set up properly.
Encoder Decode Control: I7mn0, MI910
I7mn0 (MS{node},MI910 on a MACRO Station) must be set up to decode the commutation encoder
properly. Usually, a value of 3 or 7 is used to provide times-4 decode of a quadrature encoder (4 counts
per encoder line). The difference between 3 and 7 is the direction sense of the encoder; set this variable
so the motor counts up in the direction desired.
I7mn0 (MS{node},MI910 on a MACRO Station) must be set up to decode the commutation encoder
properly. Usually, a value of 3 or 7 is used to provide times-4 decode of a quadrature encoder (4 counts
per encoder line). The difference between 3 and 7 is the direction sense of the encoder; set this variable
so the motor counts up in the direction desired.
The polarity sense of the Ixx72 commutation phase angle parameter must match that of I7mn0 for a
particular wiring; if it is wrong, it will lock into a position rather than generate continuous torque. A test
for determining this polarity match is given below. Remember that if I7mn0 is changed on a working
motor, change Ixx72 as well.
particular wiring; if it is wrong, it will lock into a position rather than generate continuous torque. A test
for determining this polarity match is given below. Remember that if I7mn0 is changed on a working
motor, change Ixx72 as well.
Output Mode Control: I7mn%6, MI916
I7mn6 (MS{node},MI916 on a MACRO Station) must be set to 1 or 3 to specify that outputs A and B
for Channel n are in DAC mode, not PWM. A setting of 1 puts output C (not used for servo or
commutation tasks in this mode) in PWM mode; a setting of 3 puts output C in PFM mode.
I7mn6 (MS{node},MI916 on a MACRO Station) must be set to 1 or 3 to specify that outputs A and B
for Channel n are in DAC mode, not PWM. A setting of 1 puts output C (not used for servo or
commutation tasks in this mode) in PWM mode; a setting of 3 puts output C in PFM mode.
Output Inversion Control: I7mn7, MI917
I7mn7 (MS{node},MI917 on a MACRO Station) controls whether the serial data streams to the DACs
on Channel n are inverted or not. The default value of 0 (non-inverted) is suitable for use with the
recommended Acc-8E analog interface board. Inverting the bits of the serial data stream has the effect of
negating the DAC voltage. In a commutation algorithm this is equivalent to a 180
I7mn7 (MS{node},MI917 on a MACRO Station) controls whether the serial data streams to the DACs
on Channel n are inverted or not. The default value of 0 (non-inverted) is suitable for use with the
recommended Acc-8E analog interface board. Inverting the bits of the serial data stream has the effect of
negating the DAC voltage. In a commutation algorithm this is equivalent to a 180
o
phase shift, which
would produce runaway if the system were working properly before the inversion.
Parameters to Set Up Motor Operation
Several I-variables must be set up for each Motor xx to enable and configure the sine-wave output for that
motor. Of course, Ixx00 must be set to 1 for any active motor, regardless of the output mode for that
motor, and Ixx01 bit 0 must be set to 1 to enable commutation, as covered earlier.
motor. Of course, Ixx00 must be set to 1 for any active motor, regardless of the output mode for that
motor, and Ixx01 bit 0 must be set to 1 to enable commutation, as covered earlier.
Command Output Address: Ixx02
When using PMAC-style Servo ICs for sine-wave control, Ixx02 must specify the address of an even-
numbered DAC register. In this mode, this will cause the Turbo PMAC to use both this DAC and the
next lower-numbered DAC (which is one address higher). Two channels must be used to commutate one
motor. For example, if the address of Servo IC 0 DAC 4 is specified, Turbo PMAC will use DACs 3 and
4. The following table shows the possible Ixx02 values for this mode:
When using PMAC-style Servo ICs for sine-wave control, Ixx02 must specify the address of an even-
numbered DAC register. In this mode, this will cause the Turbo PMAC to use both this DAC and the
next lower-numbered DAC (which is one address higher). Two channels must be used to commutate one
motor. For example, if the address of Servo IC 0 DAC 4 is specified, Turbo PMAC will use DACs 3 and
4. The following table shows the possible Ixx02 values for this mode: