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AKD and EtherCAT CSV Mode

General Information

With this EtherCAT Opmode, the trajectory generator is located in the control device, not in the AKD drive. In cyclic synchronous manner, the EtherCAT master provides a target velocity to the drive, which performs velocity control and torque control. If desired, the position control loop may be closed over EtherCAT.  Optionally, additive velocity and torque values may be provided by the control system in order to allow a second source for velocity and/or a torque feed forward. Measured by sensors, the drive device may provide actual values for position, velocity and torque to the control device.

In this suggested setup of a Kollmorgen AKD for CSV mode, I will be using the EtherCAT Master run-up, from PREOP to OP mode, to setup the drive's configuration.  If your EtherCAT master doesn't have this ability, you can set the drive up using Workbench and AKD parameters (don't forget to save to device).

In my examples:  My velocity command resolution is in 1/10 of a RPS (Rev per second).  Example:  A command of 20 will result in 2 RPS or 120 RPM command in the drive.  My position feedback resolution is 2^20 count/rev and is set by AKD parameter FB1.PSCALE.

CSV using fixed mapping of CoE Objects:

Index Data Description
0x1C12:00 0x00 (0) Clear SM PDO
0x1C13:00 0x00 Clear SM PDO
0x1C12:01 0x1702 Set fixed RXPDO map
0x1C12:00 0x01 One item mapped
0x1C13:01 0x1B01 Set fixed TXPDO
0x1C13:00 0x01 One item mapped
0x6060:00 0x09 Opmode = CSV
0x60C2:01 0x02 Interpolation time period
0x60C2:02 0xFD Interpolation time index
0x36E9:00 0x90 FBUS.PARAM05 = 144
0x204C:01 0x01 DS402.VELSCALENUM = 1
0x204C:02 0x0A DS402.VELSCALEDENOM = 10

CSV using flexible mapping of CoE Objects

Index Data Description
0x1C12:00 0x00 Clear RXPDO mapping
0x1C13:00 0x00 Clear TXPDO mapping
0x1A00:00 0x00 Clear 0x1A00 PDO
0x1A00:01 0x60630020 Set position feedback
0x1A00:02 0x60410010 Set status word
0x1A00:00 0x02 Two items mapped
0x1A01:00 0x00 Clear 0x1A01 PDO
0x1A02:00 0x00 Clear 0x1A02 PDO
0x1A03:00 0x00 Clear 0x1A03 PDO
0x1600:00 0x00 Clear 0x1600 PDO
0x1600:01 0x60FF0020 Set Vel cmd
0x1600:02 0x20400010 Set control word
0x1600:00 0x02 Two items mapped
0x1601:00 0x00 Clear 0x1601 PDO
0x1602:00 0x00 Clear 0x1602 PDO
0x1603:00 0x00 Clear 0x1603 PDO
0x1C12:01 0x1600 Set PDO
0x1C12:00 0x01 One RXPDO set
0x1C13:01 0x1A00 Set PDO
0x1C13:00 0x01 One TXPDO set
0x6060:00 0x09 Opmode = CSV
0x60C2:01 0x02 Interpolation time period
0x60C2:02 0xFD Interpolation time index
0x36E9:00 0x90 FBUS.PARAM05 = 144
0x204C:01 0x01 DS402.VELSCALENUM = 1
0x204C:02 0x0A DS402.VELSCALEDENUM = 10

Note 1: Recommend tuning the AKD in velocity mode before attempting to connect with an EtherCAT master. 

Note 2: If closing the position loop in the EtherCAT master, best performance if AKD's VL.KI or the EtherCAT Master's position integral gain is set to "0".  You can not have two integrators in series.

Note 3: Position loop proportional gain and velocity loop integral gain have the same impact on phase margin (stability).  When increasing the position loop proportional gain, you may need to decrease the AKD's VL.KI gain to reduce overshoot and/or oscillations.