Reading from and writing to Motor Drive using PDOs

[O.Alahmad]

Hi,

I have a MAXPOS 50/5 drive to control a BLDC motor.

So far, I have been using LabVIEW's SoftMotion plugin to control the motor's velocity.

It works fine for low speed applications, but the performance rapidly worsens at higher frequencies/accelerations. I strongly believe this is related to lag in communications.

I would therefore like to send commands to the drive directly via PDOs and/or SDOs. I have no problem with SDOs but I am not very familiar with PDO architecture. 

You can see in the attached image how I am reading velocity via SDO. It works fine. However, for PDOs I receive nothing. Perhaps I am using the wrong approach here.

Any ideas on how to use PDOs to communicate with the drive?

Regards,

Omar

[Jaimie]

Hi,

My name is Jaimie, I'm an applications engineer at National Instruments.

Sorry to hear the SoftMotion plugin  is not working as you expected. I cannot find any issues with this from looking into it although, I have found the following white paper that describes service data objects as well as process data objects which may help you in implementing them.

The Basics of CANopen

http://www.ni.com/white-paper/14162/en/

I hope this is useful to your project!

Thank you,

Jaimie

[jordans]

Hi Omar, 

Have you considered using the SDI Plugin for SoftMotion with this drive? If not, I highly recommend this since it abstracts all low level EtherCAT communications away from your programming, and provides you with the much easier SoftMotion programming. 

Now to your question, what type of performance drop do you see? It could be communications related, but there could be other things effecting the performance such as drive tuning etc.