Motion Control and Motor Drives

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How to send a step with AKD EtherCAT


I'm working with a cRIO and softmotion I would like to know how to send a Step to my Engine via AKD. In my tools of Softmotion I have several type of move (Line, Arc, Contour) but I don't have a Step. Thanks for your answer  


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Message 1 of 10

Instead of using a complete motion, you can use the invoke node Write Position Setpoint inside a loop (preferably TimedLoop) for position control mode and alter the value inside the loop once from one iteration to the next. Keep in mind however, that:

  • You need to consider the timing, how often will the value update
  • This will case a very abrupt jerk of your axis. I suggest that you pass your position setpoint first through some sort of low-pass filter, before sending it over Ethercat to the AKD

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Message 2 of 10

Hi Lysandros,


I'm working with servo speed (Velocity) and not in Position, in some example of SoftMotion I can see an example who name "Axis Velocity" I think it'll be fine for me. 


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Message 3 of 10


See in this attached the "Axis Velocity Override.lvproj"

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Message 4 of 10


I am not accustomed to the SoftMotion Express VIs, therefore cannot advise you on this.

The way I would approach this, is to cyclically send velocity setpoint commands to the motor drive. This will not have the comfort of smooth starting and stopping procedure and might require caution to avoid aburpt movements,  but you have other freedoms.


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Message 5 of 10

Hi Lysandros,

Thanks for your discuss, your proposition seems simple, I'll try this method. But I would like to ask you a question (see attachment) In the first we define the method to work (velocity and 2 parameters : Velocity and Accel) after the setpoint unlike your screen shot this value is a percentage of the Velocity enter previously ! Do you tell me if you already have to try with a real engine or is it a simulation? Thanks for your discuss  

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Message 6 of 10


I have juste to modify the projet "Axis Velocity Override" to Axis Velocity Setpoint (simulation only) and you can see in this attached I've an error -77004 "Axis when setting 'Axis Control Mode' on Axis 1 at Nœud de propriété (arg 1) dans Axis Velocity" have you got an idea for me ?

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Message 7 of 10


as mentioned, I have not used the express VI's and the override functions, only the invoke and property nodes. Make sure, that the motor/drive is correctly enabled and that you have the suitable control mode (velocity when you setpoint the velocity, position when you setpoint the position). Writing setpoints when the motor is not enabled may produce this error.

With AKD drives for example, one has to make sure, that the settings in Labview and the settings in the motor manufacturer software do not contradict each other.

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Message 8 of 10


"one has to make sure, that the settings in Labview and the settings in the motor manufacturer software do not contradict each other" After recommendation I only use the parameters for the Kollmorgen but in my example I only working with the Simulated Axis (see in this attached) normally it'll work isn't it ?  

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Message 9 of 10

I have not tried the simulated axis, only real axis. I wouldn't recommend prototyping motion control with the simulated axis, because in reality there are other implications (communication to the drive, limit switches, operating modes). Do you know how to add real axis in Labview? Also, download the AKD Kollmorgen Workbench program and connect to your AKD over Ethernet via the configuration port. "Find" your drive in Workbench and make sure that:

1) Command source is 1-FieldBus (else the drive will expect to be in service mode or it wait for an analog voltage at its input terminals, old fashioned)

2) Operating mode is 1-Velocity Mode


In this program you can also check parallel to Labview, if your axis is enabled or not, if there are errors, or if limits are exceeded. There are many, many options and settings. Consult also:


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Message 10 of 10