only can read state_interface, cannot write to command_interface

[gitzhangomc]

My servo drive is a 1-to-3 type, with one ECAT slave controlling three servo motors. Currently, the ROS2 EtherCAT driver I configured can read all joints state_interface but cannot write to the command_interface. What could be the issue? This is my Ethercat slave configuration file:

Configuration file for Maxon EPOS3 drive

vendor_id: 0x00000748
product_id: 0x0000000B
assign_activate: 0x0300 # DC Synch register
auto_fault_reset: false # true = automatic fault reset, false = fault reset on rising edge command interface "reset_fault"
auto_state_transitions: true

rpdo: # RxPDO = receive PDO Mapping

• index: 0x1600
  channels:
  • {index: 0x6040, sub_index: 0, type: uint16} # Control word
  • {index: 0x607a, sub_index: 0, type: int32, command_interface: position, default: .nan} # Target position
  • {index: 0x6060, sub_index: 0, type: int8} # Mode of operation
  • {index: 0x27FE, sub_index: 0, type: uint8} # Dummy Byte
• index: 0x1610
  channels:
  • {index: 0x6840, sub_index: 0, type: uint16} # Control word
  • {index: 0x687a, sub_index: 0, type: int32, command_interface: position, default: .nan} # Target position
  • {index: 0x6860, sub_index: 0, type: int8} # Mode of operation
  • {index: 0x2FFE, sub_index: 0, type: uint8} # Dummy Byte
• index: 0x1620
  channels:
  • {index: 0x7040, sub_index: 0, type: uint16} # Control word
  • {index: 0x707a, sub_index: 0, type: int32, command_interface: position, default: .nan} # Target position
  • {index: 0x7060, sub_index: 0, type: int8} # Mode of operation
  • {index: 0x37FE, sub_index: 0, type: uint8} # Dummy Byte
    tpdo: # TxPDO = transmit PDO Mapping
• index: 0x1a00
  channels:
  • {index: 0x6041, sub_index: 0, type: uint16} # Status word
  • {index: 0x6064, sub_index: 0, type: int32, state_interface: position} # Position actual value
  • {index: 0x6077, sub_index: 0, type: int16, state_interface: torque} # Torque actual value
  • {index: 0x6061, sub_index: 0, type: int8} # Mode of operation display
  • {index: 0x27FF, sub_index: 0, type: uint8} # Dummy Byte
  • {index: 0x603F, sub_index: 0, type: uint16, default: 0} # Error Code
  • {index: 0x60F4, sub_index: 0, type: int32, default: 0} # Following Error Actual Value
• index: 0x1a10
  channels:
  • {index: 0x6841, sub_index: 0, type: uint16} # Status word
  • {index: 0x6864, sub_index: 0, type: int32, state_interface: position} # Position actual value
  • {index: 0x6877, sub_index: 0, type: int16, state_interface: torque} # Torque actual value
  • {index: 0x6861, sub_index: 0, type: int8} # Mode of operation display
  • {index: 0x2FFF, sub_index: 0, type: uint8} # Dummy Byte
  • {index: 0x683F, sub_index: 0, type: uint16, default: 0} # Error Code
  • {index: 0x68F4, sub_index: 0, type: int32, default: 0} # Following Error Actual Value
• index: 0x1a20
  channels:
  • {index: 0x7041, sub_index: 0, type: uint16} # Status word
  • {index: 0x7064, sub_index: 0, type: int32, state_interface: position} # Position actual value
  • {index: 0x7077, sub_index: 0, type: int16, state_interface: torque} # Torque actual value
  • {index: 0x7061, sub_index: 0, type: int8} # Mode of operation display
  • {index: 0x37FF, sub_index: 0, type: uint8} # Dummy Byte
  • {index: 0x703F, sub_index: 0, type: uint16, default: 0} # Error Code
  • {index: 0x70F4, sub_index: 0, type: int32, default: 0} # Following Error Actual Value

[wei1224hf]

1600 and 1a00 , these 2 channels are enough , delete others
1a00 is TPDO mapping ,not rpdo,
your yaml config file is wrong ,

[wei1224hf]

here is the right format :

`

Configuration file for Maxon EPOS3 drive

vendor_id: 0x000000fb
product_id: 0x64400000
assign_activate: 0x0300 # DC Synch register
auto_fault_reset: false # true = automatic fault reset, false = fault reset on rising edge command interface "reset_fault"
sdo: # sdo data to be transferred at drive startup

• {index: 0x60C2, sub_index: 1, type: int8, value: 10} # Set interpolation time for cyclic modes to 10 ms
• {index: 0x60C2, sub_index: 2, type: int8, value: -3} # Set base 10-3s
  rpdo: # RxPDO = receive PDO Mapping
• index: 0x1603
  channels:
  • {index: 0x6040, sub_index: 0, type: uint16, default: 0} # Control word
  • {index: 0x607a, sub_index: 0, type: int32, command_interface: position, default: .nan} # Target position
  • {index: 0x60ff, sub_index: 0, type: int32, default: 0} # Target velocity
  • {index: 0x6071, sub_index: 0, type: int16, default: 0} # Target torque
  • {index: 0x60b0, sub_index: 0, type: int32, default: 0} # Offset position
  • {index: 0x60b1, sub_index: 0, type: int32, default: 0} # Offset velocity
  • {index: 0x60b2, sub_index: 0, type: int16, default: 0} # Offset torque
  • {index: 0x6060, sub_index: 0, type: int8, default: 8} # Mode of operation
  • {index: 0x2078, sub_index: 1, type: uint16, default: 0} # Digital Output Functionalities
  • {index: 0x60b8, sub_index: 0, type: uint16, default: 0} # Touch Probe Function
    tpdo: # TxPDO = transmit PDO Mapping
• index: 0x1a03
  channels:
  • {index: 0x6041, sub_index: 0, type: uint16} # 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: 0x6077, sub_index: 0, type: int16, state_interface: effort} # Torque actual value
  • {index: 0x6061, sub_index: 0, type: int8} # Mode of operation display
  • {index: 0x2071, sub_index: 1, type: int16} # Digital Input Functionalities State
  • {index: 0x60b9, sub_index: 0, type: int16} # Touch Probe Status
  • {index: 0x60ba, sub_index: 0, type: int32} # Touch Probe Position 1 Positive Value
  • {index: 0x60bb, sub_index: 0, type: int32} # Touch Probe Position 1 Negative Value
    `

[gaiyi7788]

I have a similar confusion. Because in a one-to-many slave, each motor has a corresponding address to control the quantities position and speed respectively. If the command_interface has the same name, I don't know which motor to control.

[dpflexvn]

Hi @gitzhangomc ,
I think you should try with 1 servo motor first.
I tried with EtherCAT 1.5.2 & Tsino Dynatron, but same issue as you. I will try EtherCAT 1.6 in next week and share.
What is your OS ?. kernel version ? ROS version ?.

[JensVanhooydonck]

You could try to add 3 different config files.
one with index: 0x1600 and 0x1a00, one with 0x1610 and 0x1a10 and the last one with 0x1620 and 0x1a20.
So you can select the config file for one specific joint.