Rockwell Automation 8520 9/Series CNC Integration Maintenance Manual Documentation Set - Manual (Page 109)

Section 3A
Primary 9/230 Components
3A-26
The Digital Servo control is a function at the 9/230 Digital processor
board. The control calculates positioning and velocity data and processes
the data to generate the necessary digital drive signals. These signals are
sent to the digital amplifiers which power the servo motors of the machine.
The 9/230 Digital may control up to three closed loop axes and one open
loop axis (typically used for a spindle).
The control receives position data from the axis feedback devices. On a
1394, system position data is converted to an A quad B signal in the 1394
drives system module. The control combines this position feedback data
with the interpolated commands from the control to generate the command
signals that are outputs to the servo amplifiers.
The 9/230 control is designed to make the servomotors run with optimum
performance. The maximum feedrates are limited by the mechanical
abilities of the machine. System gain and the maximum allowable
following error also limit the feedrates. These limits are entered as AMP
parameters. Refer to the 9/Series CNC AMP Reference Manual,
publication 8520-6.4, for more information.
Table 3A.J lists the digital servo output specifications. Refer to Table 3A.I
for 8520 encoder feedback input specifications or appendix H for 1394
systems. Be aware that encoders or resolvers are mounted directly to the
digital motor shaft before they are shipped and should not be removed.
Use only if you intend to use a second feedback device for an axis.
Table 3A.J
Digital Servo Interface Output Specifications
Item Specification Remark
PWM Output
(8520 digital only)
PWM Frequency Approx. 2.0 KHz
(8520 digital only)
PWM Signal Type RS-422-A
Comutated Output
(1394 digital only)
Comutated Signal
IA and IB
Approx. 1000 Hz ( ± 12 bits)
DAC Output Output Voltage Range ± 10V
Resolution 2.44mV ( ± 12 bits)
Sampling Frequency 1000 Hz
Output Current 5mA Max.
Load Capacitance 0.01 m F Max.
3A.7.2
Digital Servo Operation and
Specifications