Ask Your Question

Rosserial checksum error

asked 2016-01-17 19:06:47 -0500

AgentNoise gravatar image

When running "rosrun rosserial_python /dev/ttyACM0" I get the error message "wrong checksum for topic id and msg". After that it may continue to connect but the error "Serial Port read returned short (expected 78 bytes, received 5 instead)." comes up, or it may just not connect and keep trying. Whats weirder is if I restart the PC and run the code it works fine, I can launch RVIZ, with "roslaunch robot_description" and it will show me the range sensor and move about as i move my hand to and from the sensor. The next time I run it I get the above errors.

The code I am using is below. pretty basic for the tf stuff, really just copied the arduino copy as a test

#include <NewPing.h>
#include <ros.h>
#include <ros/time.h>
#include <sensor_msgs/Range.h>
#include <tf/transform_broadcaster.h>

//////////////////ROS Vars and OBJECTS///////////////////
ros::NodeHandle  nh;
sensor_msgs::Range range_msg;
ros::Publisher pub_range( "/ultrasound", &range_msg);
geometry_msgs::TransformStamped t;
tf::TransformBroadcaster sonar_broadcaster;

char base_link[] = "/base_link";  //set the TF child frame 
char odom[] = "/odom";
char frameid[] = "/ultrasound";
//////////////////ROS Vars and OBJECTS///////////////////

//////////////////SONAR Vars and OBJECT///////////////////
int sonar_pin =12;
NewPing sensor(sonar_pin, sonar_pin, 25);
//////////////////SONAR Vars and OBJECT///////////////////

void setup()

  t.header.frame_id =  frameid;
  t.child_frame_id = base_link;

  range_msg.radiation_type = sensor_msgs::Range::ULTRASOUND; //set the message type and the sensor radiation type
  range_msg.header.frame_id = frameid;
  range_msg.field_of_view = (10.0/180.0) * 3.14;
  range_msg.min_range = 0.0;
  range_msg.max_range = 10;

  digitalWrite(sonar_pin, HIGH); //turn internal pull-up resistor on

long range_time;

void loop()

  //publish the adc value every 50 milliseconds
  //since it takes that long for the sensor to stablize
  if ( millis() >= range_time )

    t.header.frame_id = frameid;
    t.child_frame_id = base_link;
    t.transform.translation.x = 1.0; 
    t.transform.rotation.x = 0.0;
    t.transform.rotation.y = 0.0; 
    t.transform.rotation.z = 0.0; 
    t.transform.rotation.w = 1.0;  
    t.header.stamp =;
    range_msg.range = sensor.ping_in();
    range_msg.header.stamp =;
    range_time =  millis() + 28;

edit retag flag offensive close merge delete

1 Answer

Sort by ยป oldest newest most voted

answered 2016-01-17 21:03:53 -0500

AgentNoise gravatar image

updated 2016-01-17 21:34:33 -0500

Well I figured out the checksum part of the issue. I was using frameid for both my tf broadcaster and the range_msg frame header id's. When I changed frameid to odom for the broadcaster it cleared it up.

I am still getting the "Serial Port read returned short" error

Edit: It appears the new ping library is what is causing the issue. If I use the function from the example it works just fine

edit flag offensive delete link more



Depending on how the ping library is implemented, it might be blocking interrupts while it waits for a response. Try calling ping_in before you publish your transform.

ahendrix gravatar image ahendrix  ( 2016-01-17 21:45:34 -0500 )edit

That seems to be close to the trick. I set it to do the range_msg first, then do the transform. I also it on a timer so there is a 50 or 250ms break between range_msg and the transform. That kind of works but after a minute or so it looses connection, reconnects and gets the error Creation of

AgentNoise gravatar image AgentNoise  ( 2016-01-17 22:12:26 -0500 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Question Tools

1 follower


Asked: 2016-01-17 19:06:47 -0500

Seen: 1,231 times

Last updated: Jan 17 '16