Connecting with a computer - GMP251

GMP251 User Guide

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User guide
  • Vaisala USB service cable (item code 242659)
  • Computer with:
    • Windows operating system
    • Terminal application (for example PuTTy, available from
    • Free USB port
    • Driver for Vaisala USB service cable installed (available on the cable installation media and at

The steps below describe how to connect to the probe using the PuTTY terminal application for Windows and a USB computer connection cable. Connecting with a computer allows you to configure and troubleshoot your probe using serial line commands.

  1. If you have not used the Vaisala USB cable before, install the driver before attempting to use the cable.
  2. Connect the USB serial interface cable between your computer and the M12 connector of the probe.
  3. Start the PuTTY application.
  4. Select Connection > Serial & USB and check that the correct COM port is selected in the Serial or USB line to connect to field. If you are using the PuTTY terminal application supplied by Vaisala, you can press the USB Finder button to open the Vaisala USB Instrument Finder program.
  5. Check that the other serial settings are correct for your connection, and change if necessary. Flow control should be set to None unless you have a reason to change it.
  6. Select Terminal. Use the following settings:
    Local Echo:
    Select Force on. This setting ensures that your typing is shown on the session window.
    CAUTION Make sure that the Send line ends with line feeds (CR+LF) option is not selected. Enabling this option can cause issues with the terminal connection.
  7. To open the connection window and start using the serial line, select Open.
    If PuTTY is unable to open the serial port you selected, it shows you an error message instead. If this happens, restart PuTTY and check the settings.