search

ros-industrial / ros_canopen

CANopen driver framework for ROS (http://wiki.ros.org/ros_canopen)
GNU Lesser General Public License v3.0
336 stars 271 forks source link

Control word read/write #377

Closed JadTawil-theonly closed 2 years ago

JadTawil-theonly commented 4 years ago

Does Ros-canopen assume that the control word (0x6040) is read/write access. Is it compatible with firmware in which the control word is write-only ?

mathias-luedtke commented 4 years ago

Does Ros-canopen assume that the control word (0x6040) is read/write access.

Write access should be sufficient, as long as a default is set in the EDS file. If no default is set, the current value will be read at initialization, because canopen_402 only changes certain bits.

firmware in which the control word is write-only

I doubt that this is DSP 402-compliant..

JadTawil-theonly commented 4 years ago

So you are saying that canopen_402 will read the default, and update the control word internally based on all the changes it makes to it, but would never read it directly from the controller, in the case it is write-only.

I am using the following: https://www.applied-motion.com/sites/default/files/hardware-manuals/CANopen_Manual_920-0025L.pdf

In which case the control word is wo..

mathias-luedtke commented 4 years ago

Normally, it reads the actual value at initialization. This way previously set bit are kept as-is. If the default does not match the current value, this might lead to unintended effects.

JadTawil-theonly commented 4 years ago

So If the control word is write only, the program gracefully proceeds at initialization? The reason im asking is because i am struggling to get the driver to work with the canopen controller from Applied Motion. I posted on ros answers my troubleshooting. (https://answers.ros.org/question/341810/ros-canopen-initialization-fails/). I am trying to figure out what the pointer crash is and i am curious whether it can have something to do with this incorrect implementation detail of wo control word. Has anyone ever tested a controller with wo control word?

mathias-luedtke commented 4 years ago

I doubt that this is DSP 402-compliant..

I just double checked, 0x6040 is supposed to have acces type rw or rww.

So If the control word is write only, the program gracefully proceeds at initialization?

Only, if a default is set. If not, it will probably crash with an AccessException.

whether it can have something to do with this incorrect implementation detail of wo control word

Did you check if the object is writable? Sometimes the EDS/documentation is wrong..