vinjk's profile - activity

Ok........

Hi gvdhoorn, I posted the question here because this code was given in ROS wiki http://wiki.ros.org/Industrial/Tutori...

Do you know where I can find the latest version?

The average time calculation in http://kaist-ros-pkg.googlecode.com/s... Says milliseconds but it seems to me it should be microseconds.

Shouldn't it be microseconds? Can anyone clarify this for me?

is roscore running?

This is how odometry is reset for Kobuki:

void KobukiRos::subscribeResetOdometry(const std_msgs::EmptyConstPtr /* msg */)
{
  ROS_INFO_STREAM("Kobuki : Resetting the odometry. [" << name << "].");
  joint_states.position[0] = 0.0; // wheel_left
  joint_states.velocity[0] = 0.0;
  joint_states.position[1] = 0.0; // wheel_right
  joint_states.velocity[1] = 0.0;
  odometry.resetOdometry();
  kobuki.resetOdometry();
  return;
}

Hope this helps.

i think you can try:

$  rostopic echo /topic_name

For the sake of your sanity, i'd recommend ROS Indigo with Ubuntu 14.04 for the very same reason you highlight in question i.e., many packages are not ready for the new distro.

I too am quite new to ROS environment and Linux...so can't really help you on how to use packages meant for indigo on jade.

Thank you guys for your time.

@William I had tried that as well

Hi @William , @ahendrix

I solved the problem. I did as per William's suggestion used UInt8MultiArray datatype. But before writing it to the serial port I convert it to string.

void write_callback(const std_msgs::UInt8MultiArray::ConstPtr& msg)
{
    std::string str(msg->data.begin(), msg->data.end());
    ser.write(msg->data);
}

I used the command below (just an example) to publish to topic /write

rostopic pub /write std_msgs/UInt8MultiArray '{data: [64,64,11,1,1,1,2,208,32,13,10]}'

This is the exact command I tried to run

rostopic pub /write -r 100 std_msgs/String @@1233

[character limit reached in prev comment so writing this here]

I executed this in another terminal

rostopic pub /write std_msgs/UInt8MultiArray '{data: [82, 79, 83]}' -r 1

tried as you suggested. Used std_msgs/UInt8MultiArray instead of std_msgs/String

void write_callback(const std_msgs::UInt8MultiArray::ConstPtr& msg){        
    //ROS_INFO_STREAM("Writing to serial port " << msg->data);
    ser.write(msg->data);
}

Nothing is send or received

Sorry about that. The program is the same one made by garyservin (see the link). I've posted the program in my question for your convenience. It's C++ program.

Hi all,

I am new to ROS and Linux. I am using ROS Indigo on Ubuntu 14.04 LTS. I am trying to establish serial communication with an microcontroller using ROS serial package ( https://github.com/wjwwood/serial ). Came across an example program by garyservin ( https://github.com/garyservin/serial-... ). The program works well.

The instruction packet I want to send to MCU has start bytes "@@". However, when I try to publish to this to the topic "write" I get this error:

rostopic: error: Argument error: while scanning for the next token found character '@' that cannot start any token   in "<string>", line 1, column 1:
    @@1233
    ^

Similarly if I try to send a number I get this error:

ERROR: Unable to publish message. One of the fields has an incorrect type:
  field data must be of type str

The datatype used in the example program is std_msgs/String.

What I want to send is actually data in hex code. Something like 0x40 0x40 0x09 0x01 0x00 0x00 0x02 0x0d 0x0a

Could someone guide me on how to solve this problem?

UPDATE

#include <ros/ros.h>
#include <serial/serial.h>
#include <std_msgs/String.h>
#include <std_msgs/Empty.h>

serial::Serial ser;

void write_callback(const std_msgs::String::ConstPtr& msg){
    ROS_INFO_STREAM("Writing to serial port" << msg->data);
    ser.write(msg->data);
}

int main (int argc, char** argv){
    ros::init(argc, argv, "serial_example_node");
    ros::NodeHandle nh;

    ros::Subscriber write_sub = nh.subscribe("write", 1000, write_callback);
    ros::Publisher read_pub = nh.advertise<std_msgs::String>("read", 1000);

    try
    {
        ser.setPort("/dev/ttyACM0");
        ser.setBaudrate(9600);
        serial::Timeout to = serial::Timeout::simpleTimeout(1000);
        ser.setTimeout(to);
        ser.open();
    }
    catch (serial::IOException& e)
    {
        ROS_ERROR_STREAM("Unable to open port ");
        return -1;
    }

    if(ser.isOpen()){
        ROS_INFO_STREAM("Serial Port initialized");
    }else{
        return -1;
    }

    ros::Rate loop_rate(5);
    while(ros::ok()){

        ros::spinOnce();

        if(ser.available()){
            ROS_INFO_STREAM("Reading from serial port");
            std_msgs::String result;
            result.data = ser.read(ser.available());
            ROS_INFO_STREAM("Read: " << result.data);
            read_pub.publish(result);
        }
        loop_rate.sleep();

    }
}

Thanks!