Windows下用PySerial通过PCAN-USB连接Schunk夹爪失败求助

Hey there, let’s work through this issue step by step—since list_ports.comports() is returning an empty list, your system isn’t recognizing the PCAN-USB adapter at the serial port level, which explains why none of the COM/USB ports you tried are working. Here’s how to debug this:

1. First, Confirm Hardware & Driver Setup #

PCAN-USB adapters don’t show up as standard serial ports out of the box—they require PEAK System’s official drivers to be recognized correctly.

• Unplug the PCAN-USB adapter, grab the latest drivers from PEAK’s official website, and install them fully.
• Plug the adapter back in, then check Windows Device Manager (look under "Ports (COM & LPT)" or "PEAK-System Hardware") to see if it’s listed with a valid COM port number. If you see a yellow exclamation mark, the driver install failed—try reinstalling or switching to a different USB port.

2. Double-Check PySerial’s Port Detection #

Sometimes serial.tools.list_ports misses devices due to driver quirks or permission issues. Try this alternative snippet to list ports more thoroughly:

import serial.tools.list_ports
ports = serial.tools.list_ports.comports()
for port, desc, hwid in sorted(ports):
        print(f"{port}: {desc} [{hwid}]")

If this still returns nothing, the problem is definitely at the system/driver level, not with PySerial itself.

3. Critical Note: PySerial Might Not Be the Right Tool! #

Wait a second—Schunk grippers typically communicate via CAN bus, not standard RS-232 serial. PySerial is designed for serial ports, but PCAN-USB is a CAN bus adapter. You’re probably using the wrong library here.

Instead, use a CAN-specific library like python-can which natively supports PEAK PCAN adapters. Here’s a quick test to get you started:

import can

# Initialize the PCAN adapter (adjust channel/bitrate to match your gripper's specs)
bus = can.interface.Bus(interface='pcan', channel='PCAN_USBBUS1', bitrate=500000)

# Send a test message (you'll need Schunk's official CAN protocol docs for valid commands)
msg = can.Message(arbitration_id=0x123, data=[0x01, 0x02], is_extended_id=False)
try:
    bus.send(msg)
    print("Message sent successfully")
except can.CanError:
    print("Message NOT sent")

Don’t forget to install python-can first with pip install python-can.

4. Permission Fixes (For Linux/macOS Users) #

If you’re on a non-Windows system, you might need to grant your user access to CAN/serial devices:

# Linux: Add user to dialout group
sudo usermod -aG dialout $USER
# macOS: Add user to uucp group
sudo dscl . append /Groups/uucp GroupMembership $USER

Log out and back in after running these commands for the changes to take effect.

5. Physical Connection Checks #

• Double-check that the PCAN-USB is securely connected to both your PC and the Schunk gripper’s CAN port.
• Ensure the CAN bus has proper termination: many grippers require a 120Ω resistor between CAN_H and CAN_L if it’s the only device on the bus (or the end device in a longer bus).

内容的提问来源于stack exchange，提问作者Jianing Sun