How to solve the error "cannot marshal None unless allow_none is enabled ”

Question

Hi, I am new to ros. we are trying to interface the dynamixel Pro-42 series actuator to our hardware. we are following steps mentioned in tutorial "http://wiki.ros.org/dynamixel_controllers/Tutorials/ConnectingToDynamixelBus"

the problem is when we give command

roslaunch my_dynamixel_tutorial controller_manager.launch

on console it prints two messages that are:

load_parameter : Last successfully loaded parameter (/dev/ttyUSB0)
  "cannot marshal None unless allow_none is enabled"
File "/usr/lib/python2.7/xmlrpclib.py", line 664, in dump_nil
  raise TypeError, "cannot marshal None unless allow_none is enabled
"TypeError: cannot marshal None unless allow_none is enabled 

How do i solve this issue..

<!-- -*- mode: XML -*- -->

<launch>
<node name="dynamixel_manager" pkg="dynamixel_controllers" type="controller_manager.py" required="true" output="screen">
<rosparam>
namespace: dxl_manager
serial_ports:
pan_tilt_port:
port_name: "/dev/ttyUSB0"
baud_rate: 57600
min_motor_id: 1
max_motor_id: 25
update_rate: 20
</rosparam>
</node>
</launch>

thanks in advance..

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Originally posted by pratikshriniwar on ROS Answers with karma: 1 on 2017-07-19

Post score: 0

Answer 1

serial_ports:

pan_tilt_port:

I've no experience with that particular node or the whole Dynamixel infrastructure, but it could well be that empty values for keys in yaml dicts are not allowed.

If you don't need those parameters, either remove or comment them.

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Originally posted by gvdhoorn with karma: 86574 on 2017-07-20

This answer was ACCEPTED on the original site

Post score: 0