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

asked 2017-07-19 23:50:50 -0500

pratikshriniwar gravatar image

updated 2017-07-20 01:38:58 -0500

gvdhoorn gravatar image

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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answered 2017-07-20 01:40:09 -0500

gvdhoorn gravatar image

updated 2017-07-20 01:40:22 -0500

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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Asked: 2017-07-19 23:50:50 -0500

Seen: 917 times

Last updated: Jul 20 '17