Multiple Axis CiA402 Type on 1 EtherCAT Slave support ?

[gboolt]

Hello,

Except I did something wrong, I don't think it is possible to have a configuration with 2 (or more) CiA402 Drives on the same EtherCAT Slave, following the CiA402 SubDevice definition : https://software-dl.ti.com/processor-industrial-sw/esd/ind_comms_sdk/am243x/11_00_00_08/docs/am243x/ethercat_subdevice/example2.html.

Here below a part of configuration I would like to have (Xacro & YAML with 2 axis) :

multidrive.xacro

<?xml version="1.0"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro">
 <xacro:macro name="ec_multiple_axis" params="joint_name module_name position alias">
   <joint name="${joint_name}">
     <state_interface name="status_word"/>
     <state_interface name="position"/>
     <state_interface name="velocity"/>
     <state_interface name="mode_of_operation"/>
     <command_interface name="control_word"/>
     <command_interface name="position"/>
     <command_interface name="velocity"/>
     <command_interface name="mode_of_operation"/>
     <ec_module name="${module_name}">
       <plugin>ethercat_generic_plugins/EcCiA402Drive</plugin>
       <param name="alias">${alias}</param>
       <param name="position">${position}</param>
       <param name="slave_config">config_cia402.yaml</param>
     </ec_module>
   </joint>
 </xacro:macro>
</robot>

config_cia402.yaml

rpdo: # RxPDO = receive PDO Mapping
  - index: 0x1600
    channels: # Axis 1 
      - { index: 0x6040, sub_index: 0, type: uint16, default: 0, command_interface: control_word } # Control word
      - { index: 0x607a, sub_index: 0, type: int32, command_interface: position, default: .nan} # Target position
      - { index: 0x60ff, sub_index: 0, type: int32, command_interface: velocity, default: 0 } # Target velocity
      - { index: 0x6060, sub_index: 0, type: int16, command_interface: mode_of_operation, default: 8 } # Mode of operation
  - index: 0x1610
    channels: # Axis 2
      - { index: 0x6840, sub_index: 0, type: uint16, default: 0, command_interface: control_word } # Control word
      - { index: 0x687a, sub_index: 0, type: int32, command_interface: position, default: .nan } # Target position
      - { index: 0x68ff, sub_index: 0, type: int32, command_interface: velocity, default: 0 } # Target velocity
      - { index: 0x6860, sub_index: 0, type: int16, command_interface: mode_of_operation, default: 8 } # Mode of operation
tpdo: # TxPDO = transmit PDO Mapping
  - index: 0x1a00
    channels: # Axis 1 
      - { index: 0x6041, sub_index: 0, type: uint16, state_interface: status_word } # Status word
      - { index: 0x6064, sub_index: 0, type: int32, state_interface: position} # Position actual value
      - { index: 0x606c, sub_index: 0, type: int32, state_interface: velocity } # Velocity actual value
      - { index: 0x6061, sub_index: 0, type: int16, state_interface: mode_of_operation } # Mode of operation display
  - index: 0x1a10
    channels: # Axis 2
      - { index: 0x6841, sub_index: 0, type: uint16, state_interface: status_word } # Status word
      - { index: 0x6864, sub_index: 0, type: int32, state_interface: position } # Position actual value
      - { index: 0x686c, sub_index: 0, type: int32, state_interface: velocity } # Velocity actual value
      - { index: 0x6861, sub_index: 0, type: int16, state_interface: mode_of_operation } # Mode of operation display

is it possible to create a PR for that ?

Thanks !

[JensVanhooydonck]

You could just split each axis into its own file (with only the index of each axis in the file). However, in one of my forks i added a for: field, which does this in one file. So you can reuse the same file for multiple joint ros2_control configs.

[gboolt]

You could just split each axis into its own file (with only the index of each axis in the file). However, in one of my forks i added a for: field, which does this in one file. So you can reuse the same file for multiple joint ros2_control configs.

Thanjs @JensVanhooydonck but this works if you have different ethercat slaves for each axis. Which is not my case, I want to use SubDevices, so same slave but multiple Axis with PDOs mapped with a 0x800 offset for each Axis.

I did an implementation on one of my fork and it seem to work, maybe I can contribute it here of others would be interested.

[JensVanhooydonck]

You could just split each axis into its own file (with only the index of each axis in the file). However, in one of my forks i added a for: field, which does this in one file. So you can reuse the same file for multiple joint ros2_control configs.

Thanjs @JensVanhooydonck but this works if you have different ethercat slaves for each axis. Which is not my case, I want to use SubDevices, so same slave but multiple Axis with PDOs mapped with a 0x800 offset for each Axis.

I did an implementation on one of my fork and it seem to work, maybe I can contribute it here of others would be interested.

I'm currently using https://github.com/JensVanhooydonck/ethercat_driver_ros2/tree/reuse-controller

And then in each config file I add pdo_offset, which is the offset of each axis.

rpdo:  # RxPDO = receive PDO Mapping
  - index: 0x1601
    for: transport_1
    channels:
      - {
          index: 0x6040,
          sub_index: 0,
          type: uint16,
          default: .nan,
          command_interface: control_word,
        } # Control word +
      - {
          index: 0x6060,
          sub_index: 0,
          type: int8,
          default: 9,
          command_interface: mode_of_operation,
          # state_interface: mode_of_operation,
        } # Mode of operation +
      - { index: 0x60ff, sub_index: 0, type: int32, default: .nan, command_interface: velocity, state_interface: velocity, factor: 357.1428571429  } # Target velocity +
  - index: 0x1602
    for: transport_2
    pdo_offset: 0x0800
    channels:
      - {
          index: 0x6840,
          sub_index: 0,
          type: uint16,
          default: .nan,
          command_interface: control_word
        } # Control word +
      - {
          index: 0x6860,
          sub_index: 0,
          type: int8,
          default: 9,
          command_interface: mode_of_operation,
          # state_interface: mode_of_operation,
        } # Mode of operation +
      - { index: 0x68ff, sub_index: 0, type: int32, default: .nan, command_interface: velocity, state_interface: velocity, factor: 357.1428571429 } # Target velocity +

you don't need to use the for field, you can split up each axis into multiple files.

[hitWXF]

You could just split each axis into its own file (with only the index of each axis in the file). However, in one of my forks i added a for: field, which does this in one file. So you can reuse the same file for multiple joint ros2_control configs.

Thanjs @JensVanhooydonck but this works if you have different ethercat slaves for each axis. Which is not my case, I want to use SubDevices, so same slave but multiple Axis with PDOs mapped with a 0x800 offset for each Axis.

I did an implementation on one of my fork and it seem to work, maybe I can contribute it here of others would be interested.

I meet same problem