CRIO, Compax3, EtherCAT, servo loops

[clintoncathey]

Fairly simple application.

1. 6x Parker Compax 3 Drives
2. EtherCAT communications to NI CRIO
3. Read feedback from drives - velocity and current torque
4. Command drives - torque command into torque loop

Problems:

1. Putting the drive into torque loop mode.
   • I am using the OpMode10 xml from Parker
   • I am setting the Axis loop to the torque loop
   • however I get an error (-77115 for "Axis when setting 'Axis Loop Mode' on Az 1 at Property Node (arg 1) in cRIOmain.vi"
2. getting scan engine to switch to active mode and stay there
   • when I first power up the CRIO and run the attached code, the scan engine goes to initialization mode.  Even through the scan engine is initialization mode, the EtherCAT bus I/O updates.
   • After that first time on power up, the EtherCAT bus doesn't always work and sometimes the mode drops back to configuration.

Thanks for any pointers.  This has been a very long haul for a simple operation

[clintoncathey]

http://www.ni.com/white-paper/53657/en/

Can I also get some clarification on the table at the link above?  That table indicates that torque mode isn't possible with SDI?  However, there are commands that support torque mode even when connected to the Parker Compax3?  Also earlier this year Parker and NI resolved some differences in their EtherCAT compatibility to allow for torque mode - was that not for SDI?  If not how?

[Karl-G]

Clinton,

Some of these questions would be better suited to a Service Request, but I will clear up some of the general SDI compatibility and commissioning questions here.

SoftMotion is primarily a position controller, so the main benefits of using SoftMotion Drive Interface (SDI) with EtherCAT drives is to use SoftMotion's move types. This operates the drive in Cyclic Synchronous Position (CSP) mode, and setpoints are sent to each drive every cycle of the Scan Engine via EtherCAT PDO.

Drives supporting Profile Velocity and Profile Torque modes can be used in those modes as well by using the Write : Velocity Setpoint and Write : Torque Setpoint methods respectively. This bypasses SoftMotion's position controller, and the drive operates at that setpoint until receiving a new one. The Compatibilty table linked in your post shows drives that have been tested to work with SoftMotion in Profile Velocity and Profile Torque modes.

The Compax3 does not support Profile Torque mode, and Cyclic Synchronous Torque (mode 10) was not operational during integration testing for the SDI Plug-in creation. For this reason, the Plug-in does not change the operational mode of the drive even if a torque setpoint is written.

Finally, I would recommend starting with the Getting Started with SDI tutorial. This will get you familiar with the API modifications necessary to use SDI Axes (it's just the two additional VIs during initialization), and it should work with the drive in position mode with just the examples provided. In order for any of the SDI code to work however, you need to use the ESI (.xml) file included with the plug-in. The plug-in depends on having specific PDOs exposed in the correct order.

1. Go to the <Program Files (x86)>\National Instruments\Shared\IndComECAT\DD directory

2. Move any other ESI files for the Compax3 out of the folder

3. Make sure the SoftMotion ESI file is there (C3_EtherCAT_SoftMotion_V0208_rev2.xml)

4. Delete the EtherCAT slaves in the LabVIEW Project

5. Close and re-open LabVIEW

6. Re-add the EtherCAT slaves

[clintoncathey]

Karl-

Lots to go through and understand - thank you.

First question, " Profile Velocity and Profile Torque" in your 3rd paragraph - is that the same as "Drive-based Torque Mode" in the link?  I had initially read "Drive-based Torque Mode" as "Cyclic Synchronous Torque (mode 10)".

Second question, "The Compax3 ... Cyclic Synchronous Torque (mode 10) was not operational during integration testing for the SDI Plug-in creation. For this reason, the Plug-in does not change the operational mode of the drive even if a torque setpoint is written..." - so this sounds like I can't use SDI for cyclic torque mode with the Compax 3 at all.  I can read from the Compax3 as a variable (without creating a SDI axis).  So is there a way to write without SDI?

Thank you and I'll be reviewing your other comments.  Also, I've submitted a ticket for assistance per your recommendation.  Still good to get feedback from more experienced users.

CC

[Karl-G]

Clinton,

The Drive-based Torque Mode typically corresponds to Profile Torque mode, and the Drive-Based Velocity Mode typically corresponds to Profile Velocity mode. The reason for the 'typically' is that some drives only support Cyclic Synchronous Torque or Velocity (the Mitsubishi MR-J4-TM drive is an example of this), in which case the SDI Plug-in modifies the mode the drive is placed in when the Write Velocity Setpoint or Write Torque Setpoint methods are used.

There actually are few functional differences between DS402's Profile and Cyclic Synchronous modes for velocity and torque. They both use the same PDOs to set the target value and read the feedback value. The main difference is that the Profile modes use a Target Slope and Profile Type to limit the rate of change (hence the drive performing the profiling). With Cyclic Syncronous modes, it is essentially operating with infinite "slope", allowing the EtherCAT Master to perform the profiling.

Cyclic Synchronous Torque mode could have been used in place of Profile Torque mode on the Compax3, but it was not working when the plug-in was made. In the current SDI Plug-in implementation, the torque setpoint is unused. I tested again with the Compax3, and it still does not respond to torque setpoints when placed in CST mode.

These are seen as 'extra' features to an SDI Plug-in, as the main goal of SDI is to allow full position control of the drive using SoftMotion's API with little to no modification to ESI files or configuration files by the user. It is possible to use the drive as a 'normal' EtherCAT Slave device in LabVIEW and not use SDI to control it. In that case, you can write the PDOs and SDOs with the EtherCAT API to try to get torque mode working with your drive. If you immediately need torque control of an EtherCAT drive, Parker's newer P Series servo drives work well with Profile Torque mode, as do many of the other supported drives.

[projects5]

Hi Sir,

    I am also trying to communicate Compax3 from Parker with CRIO controller, but communication not developed, can you please share compax configuration and NI file along with xml you used for communication.

Please support.

[Trevor.H]

Hi there!

I personally haven't used that motor configuration, but thought I might chime in.  Since this post is over half a year old, there is a chance the OP may not be checking it.  If they are, you may be able to get a quick answer.  If not, it may be worthwhile to make a new forum post, as that will have more visibility.