Detailed Wiring Information
05/2008
Danaher Motion
46
S200-CNS Product Manual
Outer Shield
Motor Connector Shield
Motor W ires
Drain W ire
PE W ire
Feedback
Outer Shield
(Connect to SFD Shell)
Feedback
Inner Shield
(Connect to Logic GND)
SFD Comm unication
twisted pair
Optional Foil Shield Shield
SFD Return
(Inner Drain W ire
and inner shield)
SFD +5 VDC
Outer Jacket
Jacket
Inner Jacket
Composite Cable Cross-Section
There can be substantial capacitance between the power wires and adjacent feedback shield in a
composite cable. Some of the PWM ampere level spikes tend to return in this adjacent shield. In
effect, the power stage voltage and current
drive
the feedback shield nearest to the power wires. In
a single-shielded feedback cable this
driven
shield is also around the feedback data wires, so some
coupling can occur. With double, concentric feedback shields, the
driven
shield is the outer of the
two feedback shields, and interposed between the
driven
shield and feedback data wires is the inner
feedback shield. Typically, the inner feedback shield is isolated from the connector shells and
connected to the return for the power supply powering the feedback device.
NOTE
A raw cable with two pairs of twisted, shielded feedback sections inside a
composite cable is electrically the same as single feedback shielding. There
may physically be two feedback shields in such a cable, but these shields are
not concentric. There is only one shield between the power wires and
feedback wires, where with double, concentric feedback shields, there are two.
SFD +5 and Gnd Resistance Spec
To insure that the SFD + 5 voltage at the SFD inside the motor is within specification, the voltage
drop total in the SFD + 5 V wire and SFD + 5 V RTN wire must not be greater than 0.5 V at 150 mA.
For this reason, a cable requirement is that the total resistance of the feedback SFD + 5 V wire plus
SFD + 5 V RTN wire must be < 3.33
Ω
(at 20° C). In practice, this means that for long cables, the
AWG wire gage needs to be considered.
NOTE
The inner shield of the a double, concentric feedback cable, when isolated
from the terminating connector shells, can also function as a conductor to
carry some or all of the SFD + 5 V RTN current. This is useful to keep the total
SFD + 5 and RTN resistance within specification on long cables without having
large diameters.
Feedback Characteristic Impedance
Danaher Motion's S200 feedback cables are designed to have a feedback data pair differential
impedance of 81
Ω
(at 1 MHz). Impedances in the range of 50 to 100
Ω
, while not tested, will likely
work properly with the S200.
Purchase a Danaher Motion-built composite feedback cable, review its construction, and test its
performance. There are many ways to connect the multiple shields of a composite cable. A good
way to understand how the Danaher Motion composite cable is built is to buy a short Danaher
Motion S200 composite cable, open it up, and see how the shields at both the motor and drive end
are connected.
