Subscriber failed Deserialization Error : Rosserial
HI, I'm trying to create a subscriber but I'm getting the following error
rosrun rosserial_python serial_node.py /dev/ttyACM0
[INFO] [1580450261.541002]: ROS Serial Python Node
[INFO] [1580450261.554769]: Connecting to /dev/ttyACM0 at 57600 baud
[INFO] [1580450263.710550]: Note: publish buffer size is 280 bytes
[INFO] [1580450263.711406]: Setup publisher on my_topic [dbw_mkz_msgs/SteeringCmd]
[INFO] [1580450263.720098]: Note: subscribe buffer size is 280 bytes
[INFO] [1580450263.721023]: Setup subscriber on /vehicle/steering_cmd [dbw_mkz_msgs/SteeringCmd]
Traceback (most recent call last):
File "/opt/ros/kinetic/lib/rosserial_python/serial_node.py", line 89, in <module>
client.run()
File "/opt/ros/kinetic/lib/python2.7/dist-packages/rosserial_python/SerialClient.py", line 504, in run
self.callbacks[topic_id](msg)
File "/opt/ros/kinetic/lib/python2.7/dist-packages/rosserial_python/SerialClient.py", line 107, in handlePacket
m.deserialize(data)
File "/opt/ros/kinetic/lib/python2.7/dist-packages/dbw_mkz_msgs/msg/_SteeringCmd.py", line 133, in deserialize
raise genpy.DeserializationError(e) #most likely buffer underfill
genpy.message.DeserializationError: unpack requires a string argument of length 18
The code im using is as follows
#include <ros.h>
#include <dbw_mkz_msgs/SteeringCmd.h>
#include <std_msgs/Float64.h>
#include <std_msgs/Float32.h>
float t;
ros::NodeHandle nh;
dbw_mkz_msgs::SteeringCmd msg;
void messageCb(const dbw_mkz_msgs::SteeringCmd& msg1)
{
msg.count = msg1.count;
digitalWrite(13, HIGH - digitalRead(13));
}
ros::Subscriber<dbw_mkz_msgs::SteeringCmd> sub("/vehicle/steering_cmd", &messageCb);
ros::Publisher p("my_topic", &msg);
void setup()
{
Serial.begin(115200);
pinMode(13, OUTPUT);
nh.initNode();
nh.subscribe(sub);
nh.advertise(p);
}
void loop()
{
t = msg.count;
p.publish(&msg);
nh.spinOnce();
delay(1);
}
Any idea on what i'm doing wrong here?
Just as in #q341697, you appear to have a very short
delay(1). Would be worth checking whether increasing that helps.Naah didn't work. It is not setting up the subscriber.
Try removing the Serial.begin statement as that is setting the Serial speed to 115200; but your terminal output from your serial_node says it is reading data at 57600. A mismatch in speed will mean it cannot decode the data correctly.
That was my inital guess as well. However no it didn't work.
Regardless of whether it fixed your issue: it needs to go, as what @nickw writes is true. It will never work this way.
The next thing I would try would be to change
to
as you are using t to set one of the fields in msg in the main loop and then publishing the message, but t will not be initialised to a known value until you receive a message on the topic you subscribe to.