# URL Scheme

There are two ways to open a connection to an Ftdi object.

The recommended way to open a connection is to specify connection details using a URL. The URL scheme is defined as:

    ftdi://[vendor][:[product][:serial|:bus:address|:index]]/interface

where:

- vendor: the USB vendor ID of the manufacturer

  - ex: `ftdi` or `0x403`

- product: the USB product ID of the device

  - ex: `232h` or `0x6014`

  - Supported product IDs: `0x6001`, `0x6010`, `0x6011`, `0x6014`, `0x6015`

  - Supported product aliases:

    - `232`, `232r`, `232h`, `2232d`, `2232h`, `4232h`, `230x`

    - `ft` prefix for all aliases is also accepted, as for example `ft232h`

- `serial`: the serial number as a string. This is the preferred method to uniquely identify a specific FTDI device. However, some FTDI device are not fitted with an EEPROM, or the EEPROM is either corrupted or erased. In this case, FTDI devices report no serial number

  Examples:

    - `ftdi://ftdi:232h:FT0FMF6V/1`

    - `ftdi://:232h:FT0FMF6V/1`

    - `ftdi://::FT0FMF6V/1`

- `bus:addess`: it is possible to select a FTDI device through a bus:address pair, specified as hexadecimal integer values.

  Examples:

    - `ftdi://ftdi:232h:10:22/1`

    - `ftdi://ftdi:232h:10:22/1`

    - `ftdi://::10:22/1`

  Here, bus `(0x)10` = 16 (decimal) and address `(0x)22` = 34 (decimal)

- `index`: an integer - not particularly useful, as it depends on the enumeration order on the USB buses, and may vary from on session to another.

- `interface`: the interface of FTDI device, starting from 1

  - `1` for 230x and 232* devices,

  - `1` or `2` for 2232* devices,

  - `1`, `2`, `3` or `4` for 4232* devices

All parameters but the interface are optional, PyFtdi tries to find the best match. Therefore, if you have a single FTDI device connected to your system, `ftdi:///1` should be enough.

You can also ask PyFtdi to enumerate all the compatible devices with the special `ftdi:///?` syntax. This syntax is useful to retrieve the available FTDI URLs with serial number and/or bus:address selectors.

There are several APIs available to enumerate/filter available FTDI device. See ftdi - FTDI low-level driver.

Note that opening an FTDI connection with a URL ending with ? is interpreted as a query for matching FTDI devices and immediately stop. With this special URL syntax, the avaialble devices are printed out to the standard output, and the Python interpreter is forced to exit (SystemExit is raised).

When simple enumeration of the available FTDI devices is needed - so that execution is not interrupted, two helper methods are available as `pyftdi.ftdi.Ftdi.list_devices()` and `pyftdi.ftdi.Ftdi.show_devices()` and accept the same URL syntax.

## Opening a connection

### URL-based methods to open a connection

    open_from_url()
    open_mpsse_from_url()
    open_bitbang_from_url()

### Device-based methods to open a connection

You may also open an Ftdi device from an existing PyUSB device, with the help of the `open_from_device()` helper method.

    open_from_device()
    open_mpsse_from_device()
    open_bitbang_from_device()

### Legacy methods to open a connection

The old, deprecated method to open a connection is to use the `open()` methods without the `_from_url` suffix, which accept VID, PID, and serial parameters (among others).

    open()
    open_mpsse()
    open_bitbang()

See the ftdi_urls tool to obtain the URLs for the connected FTDI devices.