Installation manual

Danaher Motion Kollmorgen Wiring
SERVOSTAR
®
S and SERVOSTAR
®
CD Series 42
Sine Encoder
The SERVOSTAR can receive an analog (or sine) encoder feedback device to
monitor the motor shaft position. As opposed to a digital encoder, which
generates incremental square-wave signals, a sine encoder outputs analog
differential sinusoidal signals. These sine signals are quadrature-decoded and
passed to an interpolation circuit that breaks each 360° cycle into 256 parts
before passing it to the drive’s control board. Thus, the resolution seen by the
drive is 256 times the fundamental sinusoidal track on the motor’s encoder. The
advantage of this approach is the ability to obtain much high encoder resolution
while maintaining a relatively low input frequency through the cable and into
the SERVOSTAR. The encoder interface includes three groups of wires:
1. A/B (and complements) lines make up the encoder quadrature signals. The
signals are received differentially at 1V peak-to-peak amplitudes before
being processed by the interpolation circuitry.
2. The narrow Index pulse normally appears once per mechanical revolution
and indicates a known physical position of the shaft. This pulse is received
differentially through an op amp before being squared up and sent to the
control board.
3. Upon power up, commutation signals are used to communicate coarse
position information. The first three signal types give approximate position
information so the drive can commutate the motor forward until the Index
pulse is found (There are situations where the index signal is not available.
Course position information is used to commutate the motor indefinitely).
The fourth gives absolute information bypassing the need for the Index
signal. They are:
• No Hall signals exist if no power-up commutation signals are available.
The SERVOSTAR can excite two phases and lock the shaft in place. It
then approximates position of the locked shaft and uses only the
incremental signals to commutate forward until the index is found.
• Hall signals provide information representing the approximate location
of the motor shaft (6 transitions per electrical cycle of the motor). From
this information, the motor can six-step commutate forward until the
index signal is detected - at which time true position is known and
sinusoidal commutation begins. These signals are isolated by an opto-
coupler and can be differential or open-collector type signals.
• C/D lines are an alternative to Hall signals. These lines provide a
SIN/COS sinusoidal signal where one electrical cycle equals one
mechanical revolution (identical to single-speed resolver feedback).
Interpolation is performed on these signals: thus, absolute position is
known within 256 parts of a mechanical revolution. The motor can
commutate forward until the Index signal is detected.