canopen

import canopen import time import os # Configuration CAN_BUSTYPE = os.environ.get('CAN_BUSTYPE', 'socketcan') # e.g., 'socketcan', 'pcan', 'ixxat' CAN_CHANNEL = os.environ.get('CAN_CHANNEL', 'can0') # e.g., 'can0', 'PCAN_USBBUS1' NODE_ID = int(os.environ.get('CANOPEN_NODE_ID', '1')) EDS_FILE = os.environ.get('CANOPEN_EDS_FILE', 'example.eds') # Replace with your device's EDS file # Create a dummy EDS file for demonstration if it doesn't exist # In a real application, you would use a manufacturer-provided .eds if not os.path.exists(EDS_FILE): print(f"Warning: {EDS_FILE} not found. Using a generic one (may not work with your device).") with open(EDS_FILE, 'w') as f: f.write(""" [FileInfo] ; Generated EDS for a generic CANopen device FileName = ExampleDevice.eds FileVersion = 1.0 VendorName = Example Vendor ProductName = Example Product ProductCode = 0 RevisionNo = 1.0 CreationTime = 2023-01-01 12:00:00 [Device] DeviceType = 0x00020002 [0x1000] ; Device Type ParameterName = Device Type ObjectType = 7 DataType = 0x0007 AccessType = ro DefaultValue = 0x00020002 [0x1001] ; Error Register ParameterName = Error Register ObjectType = 7 DataType = 0x0005 AccessType = ro DefaultValue = 0x00 [0x2000] ; Example Manufacturer Specific Integer (RW) ParameterName = My Integer ObjectType = 7 DataType = 0x0007 AccessType = rw DefaultValue = 123 """) try: # Start with creating a network representing one CAN bus network = canopen.Network() # Connect to the CAN bus # The bustype and channel must match your installed python-can backend print(f"Connecting to CAN bus: bustype='{CAN_BUSTYPE}', channel='{CAN_CHANNEL}'") network.connect(bustype=CAN_BUSTYPE, channel=CAN_CHANNEL) print("Connected to CAN bus.") # Add a CANopen node with documentation from the EDS file # For a real device, replace NODE_ID and EDS_FILE with your device's info node = canopen.Node(NODE_ID, EDS_FILE) network.add_node(node) print(f"Added Node {NODE_ID} using {EDS_FILE}.") # Read a value from the object dictionary (e.g., Device Type 0x1000) device_type = node.sdo['Device Type'].raw print(f"Node {NODE_ID} Device Type (0x1000): {hex(device_type)}") # Write and read a manufacturer-specific object (e.g., 0x2000 subindex 0) # This assumes your EDS or device supports object 0x2000 try: original_val = node.sdo[0x2000].raw print(f"Original value of 0x2000: {original_val}") new_val = 456 node.sdo[0x2000].raw = new_val print(f"Wrote {new_val} to 0x2000.") read_val = node.sdo[0x2000].raw print(f"Read back value of 0x2000: {read_val}") assert read_val == new_val except canopen.sdo.SdoError as e: print(f"Could not access object 0x2000 on Node {NODE_ID}. This might be an EDS mismatch or device limitation: {e}") # For real-time data (PDOs), you'd typically start the network's processing loop # in a separate thread or call network.process() periodically. # For this quickstart, we'll just demonstrate it briefly. print("Starting network processing for 1 second...") network.nmt.state = 'OPERATIONAL' # Set node to operational for PDOs start_time = time.time() while time.time() - start_time < 1: network.process(0.01) # Process messages for 10ms time.sleep(0.01) print("Network processing finished.") except canopen.CanError as e: print(f"CANopen Error: {e}") print("Please ensure your CAN hardware is connected and the python-can backend is correctly installed.") print(f"Tried bustype='{CAN_BUSTYPE}', channel='{CAN_CHANNEL}'") except FileNotFoundError: print(f"Error: EDS file '{EDS_FILE}' not found. Please provide a valid EDS file for your device.") except Exception as e: print(f"An unexpected error occurred: {e}") finally: # Disconnect from CAN bus if 'network' in locals() and network.is_connected: print("Disconnecting from CAN bus.") network.disconnect() if os.path.exists(EDS_FILE) and 'Warning: ' in locals() and 'generic one' in locals(): # Clean up dummy EDS os.remove(EDS_FILE) print(f"Removed dummy EDS file: {EDS_FILE}")