Hello Python community,
I am currently working on a project that involves communication between a ROS (Robot Operating System) environment and an Allen-Bradley CompactLogix PLC using Modbus TCP. I have encountered an issue with the Modbus connection, and I would appreciate any guidance or insights on resolving it.
Problem Description:
I am attempting to send data from ROS to the 1769-L16ER-BB1B Allen Bradley CompactLogix PLC. However, when running the provided Python code snippet, I am encountering the following error:
Modbus Error: [Connection] Failed to connect [ModbusTcpClient 192.168.1.1:502]
Code Snippet:
python
def move_robot_thread(self):
plc_ip = '192.168.1.1'
plc_port = 502
# Create a synchronous ModbusTcpClient instance
client = ModbusTcpClient(plc_ip, plc_port)
try:
for point in self.palletizing_pattern:
x, y, z = point
x_register_value = int(x * 100) # Convert to an appropriate integer value
y_register_value = int(y * 100)
z_register_value = int(z * 100)
# Write the coordinates to Modbus registers
client.write_registers(0, [x_register_value, y_register_value, z_register_value])
print(f"Published pose: x={x}, y={y}, z={z}")
print("Waiting for response...")
# Introduce a delay (adjust the duration as needed)
time.sleep(6)
print("All poses published.")
except Exception as e:
print(f"Error during Modbus communication: {e}")
finally:
# Close the Modbus connection
client.close()
def move_robot(self):
# Create a new thread for move_robot_thread function
move_thread = threading.Thread(target=self.move_robot_thread)
# Start the new thread
move_thread.start()
Include relevant import statements
!/usr/bin/env python3
from PyQt5.QtWidgets import QApplication, QWidget, QLabel, QLineEdit, QPushButton, QVBoxLayout, QComboBox
from PyQt5.QtCore import Qt
from PyQt5.QtWidgets import QComboBox
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.figure import Figure
import matplotlib.pyplot as plt
from geometry_msgs.msg import PoseStamped
from std_msgs.msg import String
from std_srvs.srv import Trigger
from pymodbus.client import ModbusTcpClient
import rclpy
import sys
import threading
from rclpy.task import Future
import time
Additional Information:
ROS version: humble
Python version: 3.10.12
Allen Bradley PLC model: 1769-L16ER-BB1B
Network configuration: modbus tcp
Questions:
What could be causing the "Failed to connect" Modbus error?
Are there specific considerations for Modbus communication with the Allen Bradley CompactLogix PLC?
How can I troubleshoot and diagnose the Modbus connection issue?
Any help or advice on resolving this Modbus connection problem would be greatly appreciated.
Thank you,