How to automatically refresh or reload Import CSV node data?

Auto-Refresh via UDP Socket (Advanced Method)

The Import CSV node evaluates the data only once when the file path is set. To automatically refresh it, you can either use this simple workaround with a periodic timer, or opt for a more advanced solution using UDP network sockets to enable inter-process communication for automatic CSV reloading in Blender. For a full introduction on sending data to Blender from an external application, see this guide on client-server communication with Blender.

The idea is to set up a background listener thread inside Blender that continuously waits for UDP messages. Whenever it receives a message, it triggers a Python function to refresh your Import CSV nodes.

For editing the CSV files, you can download and use Visual Studio Code (VSCode), which provides a convenient workflow through the Run on Save extension, which allows you to execute a custom Python script automatically every time you save a CSV file.

In our setup, this script sends a UDP message to Blender’s listener, effectively notifying Blender that the CSV has changed and prompting it to reload the data. That way you can create a fully automated CSV workflow, eliminating the need to manually refresh your node trees whenever you edit your data.

Setting Up the File Structure in Visual Studio Code

For testing, you can quickly set up the following file structure in the Explorer panel (Ctrl+Shift+E):

my_csv_project/
│
├─ .vscode/
│   └─ settings.json      # VSCode Run On Save config
│
├─ send_reload.py         # Python script to send UDP message to Blender
├─ test.csv               # Example CSV file you want to auto-reload

Installing the "Run on Save" Extension

Next, open the Extensions panel (Ctrl+Shift+X), search for Run on Save, and click Install.

File Contents Setup

Then, create a folder named .vscode (folder name starts with period) which will contain the settings.json file. Next, open settings.json and fill it with the following content. Make sure the path to your Python executable is correct. In my setup, it is:

C:/Program Files/Blender Foundation/Blender 5.0/5.0/python/bin/python.exe

Adjust this path if your Blender installation is in a different location:

{
    "emeraldwalk.runonsave": {
        "commands": [
            {
                "match": "\\.(csv|txt)$",
                "cmd": "\"C:/Program Files/Blender Foundation/Blender 5.0/5.0/python/bin/python.exe\" send_reload.py",
                "isAsync": true
            }
        ]
    }
}

This settings.json file instructs VSCode to execute the command defined in the cmd parameter whenever a file matching the specified match pattern (in this case, .csv or .txt) is saved. The command runs the Python script send_reload.py, which opens a UDP socket (using an arbitrary port 5005 in this example) and sends a message to Blender’s listener, which we will setup later to trigger a CSV reload. Next, create send_reload.py with the following content:

import socket

UDP_PORT = 5005  # Make sure this matches the port your Blender listener is using
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.sendto(b"reload", ("127.0.0.1", UDP_PORT))
print("Reload signal sent!")

Checking the "Run on Save" Output

Next, open the Terminal via View > Terminal and click Output panel, or press Ctrl+Shift+U to open it. Make sure the dropdown on the right is set to Run on Save so you can see the output of the commands triggered when saving files.

Setting Up the Blender UDP Listener

Finally, in Blender’s Text Editor, paste the following script into the Text Editor and click Run Script. It starts a background listener on a UDP port. We use port 5005 in this example because it is generally free on most systems and matches the port used by send_reload.py.

Just make sure the port you choose is not already in use. Many ports are reserved or commonly used by other applications (see the list of port numbers).

import bpy
import socket
import threading
import time

UDP_PORT = 5005

def find_csv_nodes():
    csv_nodes = []
    for node_tree in bpy.data.node_groups:
        for node in node_tree.nodes:
            if node.bl_idname == "GeometryNodeImportCSV":
                csv_nodes.append((node_tree, node))
    return csv_nodes

def update_csv_node_inputs(csv_nodes):
    for tree, node in csv_nodes:
        path = node.inputs[0].default_value
        node.inputs[0].default_value = path

def run_csv_update():
    nodes = find_csv_nodes()
    update_csv_node_inputs(nodes)

def listen_udp():
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    s.bind(("127.0.0.1", UDP_PORT))
    print(f"[Listener] Listening on UDP port {UDP_PORT}…")

    while True:
        try:
            data, addr = s.recvfrom(1024)
            run_csv_update()
        except Exception as e:
            print("UDP listener error:", e)

threading.Thread(target=listen_udp, daemon=True).start()  # Start the listener in a background thread

The script iterates over all Import CSV nodes in your node groups and, whenever send_reload.py sends a signal, automatically updates their input values to ensure the latest CSV data is loaded.

You can also register the script so that it runs automatically the next time you open Blender, eliminating the need to run it manually.

Demo: Editing the CSV and Seeing the Refresh

Now, whenever you edit your CSV file and press Ctrl+S to save, VSCode will automatically send a UDP signal to Blender. The listener inside Blender receives this signal and refreshes all Import CSV nodes instantly.

Restarting the Blender UDP Listener

This script creates a persistent socket listener inside Blender, which means you cannot run the script multiple times simultaneously on the same port. Normally, closing Blender will terminate the listener and free the port.

However, sometimes Blender may not shut down cleanly, leaving the socket process running even after the application is closed. In such cases, you must manually terminate the process that is holding the port before restarting the listener.

To find which process is using the port, open PowerShell (or any terminal appropriate for your OS) and run:

netstat -ano | findstr 5005

This command lists all network endpoints and filters for port 5005.
In the example below, the last column shows the PID (Process ID):

Once you have the PID (e.g., 26044), terminate it by running:

taskkill /PID 26044 /F

The /F flag forces the process to close, which also closes Blender:

Additional Notes on Using Excel Viewer Extension

You can install the Excel Viewer extension to work with CSV files in a more user-friendly, spreadsheet-style interface.

After installing the extension, right-click the CSV file you want to edit and select Open With:

From the menu, choose CSV Editor:

I found the Edit CSV extension works really well for editing CSV files. After installing it, simply open your CSV file, right-click it in the Explorer, and choose Edit CSV to start editing in a spreadsheet-like view.