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SFD3 Feedback

Valid for AKM, AKMH, S300, S700


Kollmorgen motors can be delivered with internal SFD3 ( S mart F eedback D evice) Feedback. This feedback system uses a resolver for the position sensor and communicates with the drive digitally. The serial communications to the drive includes motor shaft position, motor temperature measurement, and at power up the motor catalog specifications stored inside the SFD3 in FLASH memory (plug and play).

The Smart Feedback Device (SFD3) connects to the drive with just two wires which provide dc power and ac coupled RS-485 digital serial communications.


Single cable support for SFD3 Feedbacks is available from Firmware Version 6.00 with S300 and S700 servoamplifiers. Firmware Versions from 6.00 can be uploaded to devices S300 (HWR from 4.20) and S700 (HWR from 2.30) only, devices with former hardware revisions cannot be updated.

Angle Measurement


224 = 16,777,216 counts per rev = 0.0013 arc min



Less than +/- 0.75 arc-min electrical + sensor error

- Size 10 sensor +/- 16 arc-min net
- Size 15 sensor +/- 9 arc-min net
- Size 21 sensor +/- 9 arc-min net

Electrical Noise

Less than 2-17 Rev rms at full bandwidth



More than 2000 Hz at -3 dB
More than 1000 Hz at -45 deg phase lag


Max Tracking Rate

More than 50,000 RPM


Velocity Ripple

Less than 0.2% p-p electronics only

- Size 10 sensor < 2.5% p-p net
- Size 15 sensor < 1.5% p-p net
- Size 21 sensor < 1.5% p-p net

Velocity Noise

Less than 4 RPM rms at full bandwidth

No PWM. With PWM slightly higher depending on
PWM noise coupling to internal resolver.

Digital Communications, Power Supply

Supply at the drive via Splitter Adapter

8.5 - 11V, Nominal 90 mA @ 9V, Worst Case 125 mA

Supply at SFD3 7.0 - 11V, observe line voltage drop to ensure minimum supply voltage at SFD3

Baud Rate

2.5 MBaud

Signaling - AC coupled RS-485 differential, half duplex, 8 bit data with odd parity
- Updated on demand from drive. Update period >= 50 uSec.
- Error Detection 5 bit CRC in addition to parity check

Cable Resistance

Less than 10 Ohm net; observe line voltage drop to ensure minimum supply voltage at SFD3


Operating Ambient Temperature

-20 to +120 Deg C


10% to 90% non-condensing

Storage Temperature

-40 to +135 Deg C