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Programming Principle of Using BECKHOFF EtherCAT Servo PDO Object


I'm new in EtherCAT-LabVIEW programming. Recently I need to use BECKHOFF AX5103. Currently my biggest problem is that I have no idea about how to setup of the master program to let the motor work in the torque mode.


This is my knowledge background for now:

1. I understand PDO object and know how to check the object meaning in the manual;


2. I know basic tools in LabVIEW to import the ESI file (XML format), like this (it's YASKAWA SGDV PDO imported in LabVIEW)



3. I could read other people's LabVIEW code to figure out how the servo works in this program, like this



Considering my needs to work with BECKHOFF servo, what I eager for is a programming guideline or  example for servo control. I have checked the BECKHOFF manual (System Manual - Servo Drives AX5000), but got nothing about programming guide. 


Meanwhile I checked YASKAWA's EtherCAT manual(see the hyperlink at the bottom), cross checking the LabVIEW control program I have, I found it difficult to understand. For example, the picture below (from the YASKAWA EtherCAT manual section 7.5.1) shows the diagram of Profile Velocity mode, I'm not sure this could serve as workflow chart for LabVIEW programming




Could anybody tell me where should I start?

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There are tutorials available online and some examples. You can start with Fundamentals of Motion Control:
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Sorry the reply above offers every few detail in programming guide, so it didn't help much.

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That is quite difficult. The reason is that Twincat (Programming software from Beckhoff) abstracts all these things. I mean, in Twincat you create an axis, and then you call MC_MoveAbsolute function, and it works. You will not find a lot of documentation about registers handle and operations sequences.


But, that is standardised in CanOpen motion. Try to look for "canopen motion" and "coe motion".


Normally, you can do 90% of things with controlword and statusword registers on PDO. You just have to set target position, speed, and acceleration.



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Hi,  Walker34


You are right, it's quite difficult. In the past few weeks I've been working on the ESI XML file and Beckhoff TwinCAT software on and off.


I found that people do not manipulate the PDOs directly in TwinCAT, these PDOs are encapsulated in functions provided by TwinCAT.


But I have to use motors in this way, because I must put the motor controlled by the program running on LabVIEW RT, and I have already ordered motors from Beckhoff, which adapt the SOE protocol instead of COE.

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