Arduino publisher: unable to sync with device

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I'm trying to use an IR reader and an Arduino Uno as the basis for my odometry. I'm using the attached code. The code compiles and uploads successfully to the Arduino. I then run roscore and rosrun rosserial_python serial_node.py _port:=/dev/ttyACM0 _baud:=57600 which produces the following errors:

pi@raspberrypi:~/odom_ws $ rosrun rosserial_python serial_node.py _port:=/dev/ttyACM0 _baud:=57600
[INFO] [1616083210.822040]: ROS Serial Python Node
[INFO] [1616083210.834459]: Connecting to /dev/ttyACM0 at 57600 baud
[INFO] [1616083212.945610]: Requesting topics...
[INFO] [1616083213.425535]: Wrong checksum for msg length, length 8, dropping message.
[ERROR] [1616083227.953649]: Unable to sync with device; possible link problem or link software version mismatch such as hydro rosserial_python with groovy Arduino
[INFO] [1616083227.960634]: Requesting topics...
[ERROR] [1616083242.968012]: Unable to sync with device; possible link problem or link software version mismatch such as hydro rosserial_python with groovy Arduino
[INFO] [1616083242.977686]: Requesting topics...
[ERROR] [1616083257.984978]: Unable to sync with device; possible link problem or link software version mismatch such as hydro rosserial_python with groovy Arduino

All help and feedback is much appreciated.

// Include ros.h header file and header files for all messages we'll be using
#include <ros.h>
#include <ros/time.h>
#include <tf/tf.h>
#include <nav_msgs/Odometry.h>
#include <tf/transform_broadcaster.h>

const double dx = 0.1;   // Distance increment per reading in meters
                         // Dummy variable used here for support purposes

// Instantiate node handle (allows us to create publishers and subscribers)
ros::NodeHandle nh;
nav_msgs::Odometry odom_msg;
ros::Publisher odom_pub("/odom", &odom_msg);
tf::TransformBroadcaster odom_broadcaster;

// Initial position
double x = 0.0;
double y = 0.0;
double theta = 0.0;

// Set time
ros::Time current_time = nh.now();
ros::Time last_time = nh.now();

void setup()
{

  // Enable interruption pin when going from LOW to HIGH
  // Calls Pulse_Event()
  attachInterrupt(digitalPinToInterrupt(IR_Pin), Pulse_Event, RISING);

  // Set time
  current_time = nh.now();
  last_time = nh.now();

  // Initialize node and broadcast it
  nh.initNode();
  nh.advertise(odom_pub);

}

void loop()
{
  // Process the publishing queue
  nh.spinOnce();

  // Delay in µs
  delay(1000);
}

void Pulse_Event()
{  
  // Set current time
  current_time = nh.now();

  // Calculate velocity
  double dt = (current_time.toSec() - last_time.toSec());
  double delta_x = cos(theta)*dx;
  double delta_y = sin(theta)*dx;
  double delta_th = 0.0;

  double vx = delta_x / dt;
  double vy = delta_y / dt;
  double vth = delta_th / dt;

  // Update x,y
  x += delta_x;
  y += delta_y;
  theta += delta_th;

  // Since all odometry is 6DOF we'll need a quaternion created from yaw
  geometry_msgs::Quaternion odom_quat = tf::createQuaternionFromYaw(theta);

  // Publish transform over tf
  geometry_msgs::TransformStamped odom_trans;
  odom_trans.header.stamp = current_time;
  odom_trans.header.frame_id = "odom";
  odom_trans.child_frame_id = "base_link";

  // Set transform for x,y,z coordinates
  odom_trans.transform.translation.x = x;
  odom_trans.transform.translation.y = y;
  odom_trans.transform.translation.z = 0.0;
  odom_trans.transform.rotation = odom_quat;

  // Send the transform
  odom_broadcaster.sendTransform(odom_trans);

  // Set odom header
  odom_msg.header.stamp = current_time;
  odom_msg.header.frame_id = "odom";

  // Set the position
  odom_msg.pose.pose.position.x = x;
  odom_msg.pose.pose.position.y = y;
  odom_msg.pose.pose.position.z = 0.0;
  odom_msg.pose.pose.orientation = odom_quat;

  // Set the velocity
  odom_msg.child_frame_id = "base_link ...