unlockusbmodular/index.html

<!doctype html>

<html lang="en">
<head>
  <meta charset="utf-8">

  <title>Keysight USB Modular instruments unlocker</title>

</head>

<body>
  Keysight(or Agilent) U27xx modular devices stay on 'firmware update' mode at power-on.<br>
  You can change to USBTMC device when you click the unlock button.
  <p>
    <button id="unlock">Unlock</button>
  </p>
  <script>
    document.getElementById('unlock').onclick = function() {
      let device;
      const filters = [
        {'classCode': 0x00, 'subclassCode': 0x00, 'protocolCode': 0x00},
      ];
      navigator.usb.requestDevice({'filters': filters}).then((result) => {
        device = result;
        return device.open();

      }).then(()=>{
        if (device.vendorId != 0x0957) {
          throw new Error("The device is not suitable");
        }
        return device.claimInterface(device.configuration.interfaces[0].interfaceNumber);

      }).then(()=>{
          const data = new Uint8Array([0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00]);
          return device.controlTransferOut({
            'requestType': 'vendor',
            'recipient': 'device',
            'request': 0x0C,
            'value': 0,
            'index': 0x475}, data
          );

      }).then(()=>{
        alert('Unlock Success');
      }).catch((error) => {
        alert(error);
      });
    };

  </script>
</body>
</html>