Delta Tau GEO BRICK LV User Manual
Turbo PMAC User Manual
Setting Up Feedback and Master Position Sensors
63
The rising edge of the return pulse in the DPM format is the equivalent of the rising edge of the start pulse
in the RPM format. The falling edge of the return pulse in the DPM format is the equivalent to the rising
edge of the stop pulse in the RPM format. Because Turbo PMAC is expecting a rising signal edge to
latch the timer, in this signal format the return signals should be inverted so that the ‘+’ output of the
MLDT is wired into Turbo PMAC’s ‘-’ input, and vice versa.
in the RPM format. The falling edge of the return pulse in the DPM format is the equivalent to the rising
edge of the stop pulse in the RPM format. Because Turbo PMAC is expecting a rising signal edge to
latch the timer, in this signal format the return signals should be inverted so that the ‘+’ output of the
MLDT is wired into Turbo PMAC’s ‘-’ input, and vice versa.
Hardware Setup
The PULSEn output that is used commonly to command stepper drives is used as the excitation signal for
the MLDT; typically the CHAn input that is part of encoder feedback is used to accept the response. The
PULSEn output is an RS-422 style differential line-drive pair. The CHAn input is an RS-422 style
differential line receiver pair. The use of differential pairs for both inputs and outputs is strongly
encouraged for the common-mode noise rejection it provides.
the MLDT; typically the CHAn input that is part of encoder feedback is used to accept the response. The
PULSEn output is an RS-422 style differential line-drive pair. The CHAn input is an RS-422 style
differential line receiver pair. The use of differential pairs for both inputs and outputs is strongly
encouraged for the common-mode noise rejection it provides.
On some interface boards (e.g. Acc-24E2A, Acc-24E2S), the PULSEn+/- signals are output on lines that
otherwise would be supplemental flag inputs, and jumper(s) must be installed to enable the outputs on
these lines. Consult the user manual for the board for details.
otherwise would be supplemental flag inputs, and jumper(s) must be installed to enable the outputs on
these lines. Consult the user manual for the board for details.
Remember that in the DPM signal format or equivalent (see above), the ‘+’ output of the MLDT should
be wired into the CHAn- input, and the ‘-’ output of the MLDT should be wired into the CHAn+ input.
be wired into the CHAn- input, and the ‘-’ output of the MLDT should be wired into the CHAn+ input.
Turbo PMAC Hardware-Control Parameter Setup
PFM Clock Frequency: I7m03, I6803, MI903, MI907, MI993
The pulse output uses Turbo PMAC’s pulse frequency modulation (PFM) feature. The PFM circuitry
generates periodic output pulses by repeatedly adding a command value into an accumulator. When the
accumulator overflows, an output pulse is generated.
The addition of the command value into the accumulator is performed once per PFM clock (PFMCLK)
cycle. The PFMCLK frequency is governed by I7m03 for the channels on Servo IC m, I6803 for the
supplemental channels on MACRO IC 0, and MI903, MI907, or MI993 for channels on a MACRO
Station. The default frequency of the PFMCLK for all channels is 9.83 MHz; this frequency should be
suitable for all MLDT applications.
generates periodic output pulses by repeatedly adding a command value into an accumulator. When the
accumulator overflows, an output pulse is generated.
The addition of the command value into the accumulator is performed once per PFM clock (PFMCLK)
cycle. The PFMCLK frequency is governed by I7m03 for the channels on Servo IC m, I6803 for the
supplemental channels on MACRO IC 0, and MI903, MI907, or MI993 for channels on a MACRO
Station. The default frequency of the PFMCLK for all channels is 9.83 MHz; this frequency should be
suitable for all MLDT applications.
PFM Output Frequency: Mxx07, MI926
The pulse output frequency for a channel is controlled by both the PFMCLK frequency and the PFM
command value for the channel, which is the C-output register for that channel. When used for stepper
motor applications, the PFM command value is determined by the instantaneous command velocity and
the gains of the simulated servo loop on Turbo PMAC; Ixx02 tells Turbo PMAC to write this to the PFM
command register.
For MLDT use, we will write to the PFM command register once on power-up/reset with an M-variable.
(If the interface is on a MACRO Station, the Station’s firmware will do this automatically, using the
saved value of node-specific variable MI926.) The suggested M-variable definition for this register is
Mxx07. The following table shows the registers for these suggested definitions:
command value for the channel, which is the C-output register for that channel. When used for stepper
motor applications, the PFM command value is determined by the instantaneous command velocity and
the gains of the simulated servo loop on Turbo PMAC; Ixx02 tells Turbo PMAC to write this to the PFM
command register.
For MLDT use, we will write to the PFM command register once on power-up/reset with an M-variable.
(If the interface is on a MACRO Station, the Station’s firmware will do this automatically, using the
saved value of node-specific variable MI926.) The suggested M-variable definition for this register is
Mxx07. The following table shows the registers for these suggested definitions: