Brick Motion Controller Hardware Reference Manual
26
System Wiring
For more details about Encoder Loss look into the Turbo USERs Manual chapter:
Making Your
Application Safe
.
Setting up the Analog Inputs (optional)
The Brick Motion Controller can be ordered with two or four 16-bit hi-resolution analog to digital
converters.
The Brick Motion Controller uses the Burr Brown ADS8361.
See Appendix B for partial Schematics
When selected for bipolar mode, differential inputs allow the user to apply input voltages to ±5 volts
(10Vp-p).
To read the A/D data, the user needs to set the ADC strobe word for the second gate array to I7106 =
$1FFFFF. Also, the user needs to create M-variable definitions that point to the ADC inputs (M-variables
that are used are suggested ones) for channels 5 to 8.
Bipolar
The data received is a signed 16-bit number scaled from –5V to +5V (-32768cts to 32767cts).
M5061->Y:$78105,8,116,s ;ch5 A-D channel
M5062->Y:$7810D,8,16,s ;ch6 A-D channel
M5063->Y:$78115,8,16,s ;ch7 A-D channel
M5064->Y:$7811D,8,16,s ;ch8 A-D channel
Filtered DAC Outputs Configuration (optional)
The Brick Motion Controller /-10V outputs are produced by filtering a PWM signal. This
technique has been used for some time now by some other DeltaTau products (PMAC2A-PC/104) and
many of our competitors. Although this technique does not contain the same levels of performance as a
true Digital to Analog converter (DAC), for most servo applications it is more than adequate. Passing the
PWM signal through a 10KHz low pass filter creates the +/-10V signal output. The duty cycle of the
PWM signal is what generates the magnitude the voltage output. The frequency of the PWM signal
determines the magnitude and frequency of ripple on that +/-10V signal. As you lower the PWM
frequency and subsequently increase your output resolution, you increase the magnitude of the ripple as
well as slow down the frequency of the ripple as well. Depending on the system, this ripple can effect
performance at different levels.
Both the resolution and the frequency of the Filtered PWM outputs are configured in software on the
Brick Motion Controller through the variable
I7m00
. This I7m00 variable also effects the phase and
servo interrupts. Therefore as we change I7m00 we will also have to change
I7m01
(phase clock
divider),
I7m02
(servo clock divider), and
I10
(servo interrupt time). These four variables are all related
and must be understood before adjusting parameters. I7mn6 (m=1, n=1-4) needs to be set for PWM
output.
When the analog I/O option is ordered the Brick Motion Controller comes with 2 or 4 analog (+/10VDC)
output signals. These analog output signals are filtered PWM signals, 12-bit analog outputs. These
outputs can be either single-ended or differential. For a single-ended analog output use the DACn+ side
of the signal and leave the DACn- floating; do not ground it. For a differential command output, connect
the positive side of the DACn+, and the negative side DACn-.
To limit the range of each signal to ±5V, use parameter Ixx69. Any analog output not used for dedicated
servo purposes may be utilized as a general-purpose analog output. Usually this is done by defining an
M-variable to the digital-to-analog-converter register (suggested M-variable definitions M502, M602,
