← Export CSV Logs to USB from a Node-RED Dashboard

Export CSV Logs to USB from a Node-RED Dashboard — full example

One-tap USB export for industrial data logs: detect a pendrive on Raspberry Pi, copy the CSV history and confirm on screen, all from Node-RED.

Complete, runnable program for the TouchBerry Pi (export-history-usb.js): wiring header, requirements and integration notes included.

Read-only preview.

/*
 * COMPLETE EXAMPLE — Exporting the activation history to a USB drive
 *
 * Hardware:  TouchBerry Pi (Raspberry Pi + Industrial Shields PLC, touch screen)
 * Based on:  industrial mixing project (Node-RED touch HMI)
 *
 * Requirements:
 *   - Node-RED with @flowfuse/node-red-dashboard (UI v2)
 *   - Raspberry Pi OS with USB auto-mount at /media/pi/
 *   - Activation CSV at /home/pi/logs/log_activaciones.csv
 *
 * Architecture:
 *   The operator presses "Export to USB" on the /history page. The flow
 *   detects whether a USB stick is mounted, copies the CSV with a dated
 *   name and confirms (or reports the error) with an on-screen notification.
 *
 * Flow wiring:
 *
 *   [ui-button "Export to USB"]
 *        └─> [exec 1: ls /media/pi]                     (detect USB stick)
 *              └─(stdout)─> [function 1: chooseDestination]
 *                    ├─(output 1: USB found)──> [exec 2: cp ...]  (command in msg.payload)
 *                    │        ├─(stdout)──> [function 2: notifyOk]    ─> [green ui-notification]
 *                    │        └─(stderr)──> [function 3: notifyError] ─> [red ui-notification]
 *                    └─(output 2: no USB)──> [ui-notification "Insert a USB drive"]
 *
 * Node configuration:
 *   - exec 1: fixed command "ls /media/pi", append payload disabled.
 *   - exec 2: empty command, "append msg.payload" enabled (the full
 *     command arrives already built by function 1).
 */

// ============================================================
// function 1: chooseDestination
// ------------------------------------------------------------
// Receives the stdout of "ls /media/pi". Each line is a mount
// point (a USB drive). If there is one, it builds the copy
// command with a dated name; otherwise it warns the operator.
// Output 1: cp command ready / Output 2: no USB
// ============================================================
const SOURCE = "/home/pi/logs/log_activaciones.csv";

const devices = (msg.payload || "")
    .split("\n")
    .map(d => d.trim())
    .filter(d => d.length > 0);

if (devices.length === 0) {
    msg.payload = "Insert a USB drive and try again";
    return [null, msg];
}

// Use the first mounted device; quotes in case the USB
// label contains spaces.
const destDir = "/media/pi/" + devices[0];

// Dated file name: log_activaciones_2026-06-12.csv
const today = new Date().toISOString().slice(0, 10);
const destination = destDir + "/log_activaciones_" + today + ".csv";

// 'sync' guarantees the data is written before the operator
// pulls out the USB stick.
msg.payload = `cp ${SOURCE} "${destination}" && sync`;
msg.destination = destination;         // reused by the notification
return [msg, null];


// ============================================================
// function 2: notifyOk  (stdout of exec 2)
// ------------------------------------------------------------
// cp prints nothing when everything goes well: we confirm ourselves.
// ============================================================
msg.payload = "History exported to " + (msg.destination || "the USB drive") +
              ". You can now remove the device.";
return msg;


// ============================================================
// function 3: notifyError  (stderr of exec 2)
// ------------------------------------------------------------
// Typical errors: read-only USB, no space left, removed
// mid-copy. We show the raw error for diagnosis.
// ============================================================
msg.payload = "Export error: " + msg.payload;
node.error("USB export failed: " + msg.payload, msg);
return msg;