Skip to main content

Kollmorgen Support Network

SFD Feedback | 07 Nov 2013 | |

SFD Feedback

Valid for AKM, AKMH, AKD


Kollmorgen motors can be delivered with internal SFD (Smart Feedback Device) 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 (SFD) communicates with the drive over a 4 wire interface.  Two wires supply +5V power at <150 mA and the second pair is an RS-485 digital communications link.

Angle Measurement

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

Digital Communications

Baud Rate 2.5 MBaud
  • RS-485 differential, 8 bit data with odd parity, compatible with standard UARTs
  • Update Period once every 51.2 uSec new position sample
  • Error Detection 5 bit CRC in addition to parity check
  • EEPROM Memory does a data dump when the unit powers up

Power Supply

Supply at Drive 5.0 V +/- 0.25V (+/-5%)
Supply at SFD in Motor 4.25V to 5.25V
Supply Current
  • Nominal 120 mA
  • Worst Case 150 mA
Cable Resistance +5V, GND Less than 3.3 Ohm net


Operating Ambient Temperature -20 to +120 Deg C
Humidity 10% to 90% non-condensing
Storage Temperature -40 to +135 Deg C


Back to top