System Operation
Danaher Motion Kollmorgen Speciality Electronics
18
SERVO
STAR
CD-LITE User Manual
Operational Modes
The SERVO
STAR
CD-Lite has the ability to assume different modes of operation. It is factory
configured in OPMODE=1 (Analog Velocity Controller) but may be reconfigured by the user. Not all
commands and variables are active or meaningful in every OPMODE.
OPMODE = 1
Analog Velocity Controller
. The SERVO
STAR
CD-Lite is configured as a
velocity-loop controller and is controlled via a ± 10V analog input signal.
The commanded velocity is proportional to the input voltage.
OPMODE = 3
Analog Torque (Current) Controller
. The SERVO
STAR
CD-Lite is
configured as a torque-loop controller and is controlled via a ± 10 V analog
input signal. The commanded current is proportional to the input voltage.
System I/O
This section discussions the I/O features of the C3 connector (except for the Thermostat input on C2 see
appendix). Electrical specifications are in the Quick Start Guide.
Analog Input (ANIN1)
The velocity or torque loop can receive its command from an analog voltage source and is selectable
through the OPMODE variable. The analog input to the SERVO
STAR
CD-Lite is differential. This
means that the signals received at the two inputs are subtracted from each other to create a ‘difference,’
that is used to command the rest of the system. This type of input has a high degree of noise immunity
and, in many cases, will allow for ground isolation between systems. This analog input also has a low
pass filter (ANLPFHZ) to prevent high frequency noise from entering the system.
The input voltage from the differential receiver is applied to a precise 12-bit Analog-to-Digital (A/D)
conversion system. The A/D conversion system is read by the microprocessor, 250
µ
s for the velocity
loop mode, and every 62.5
µ
s for the torque (current) loop mode of operation. Encoder-based units have
the additional benefit of a Dual Gain (ANDG) input. When enabled, the system uses two 14-bit A/D
inputs to read the user-supplied analog signal. One input is a direct reading of the ± 10V signal, while
the other incorporates a 2x gain term. When the input voltage is less than 4V, the 2x channel is used to
determine the user’s input voltage. This extends the resolution to a 15-bit equivalent. Above 4V, the
system uses the straight 14-bit conversion. Special software algorithms are used to minimize cross-over
distortion and add 0.25 V hysterisis.
Analog systems often require scaling and offset bias. The SERVO
STAR
CD-Lite adds an analog offset
(ANOFF1) variable to this reading, performs an analog deadband (ANDB) adjustment, and scales it
through velocity loop input scaling (VSCALE), or torque loop input scaling (ISCALE) before passing the
data to the selected control loop. The analog input (ANIN1) variable indicates the analog reading after
the offset (ANOFF1) and the deadband (ANDB) adjustments, but before the loop scaling. The ANIN1
variable range is ± 22500 counts (or mV).
The SERVO
STAR
CD-Lite also has an automatic analog input zeroing function. Invoking the ANZERO
command while the drive is enabled or disabled samples motor velocity over a 32 ms period and updates
ANOFF1 accordingly to cancel out analog input offset. This command uses an internal offset
mechanism that has finer resolution than ANOFF1 is capable of providing.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
