||One-Wire File System
owfs [ -c config ] -d serialport | -u | -s
[host:]port -m mountdir
1-wire is a wiring protocol and series of devices designed and
manufactured by Dallas Semiconductor, Inc. The bus is a low-power low-speed
low-connector scheme where the data line can also provide power.
Each device is uniquely and unalterably numbered during
manufacture. There are a wide variety of devices, including memory, sensors
(humidity, temperature, voltage, contact, current), switches, timers and
data loggers. More complex devices (like thermocouple sensors) can be built
with these basic devices. There are also 1-wire devices that have encryption
The 1-wire scheme uses a single bus master and multiple
slaves on the same wire. The bus master initiates all communication.
The slaves can be individually discovered and addressed using their unique
Bus masters come in a variety of configurations including serial,
parallel, i2c, network or USB adapters.
OWFS is a suite of programs that designed to make the 1-wire bus and its
devices easily accessible. The underlying principle is to create a virtual
filesystem, with the unique ID being the directory, and the individual
properties of the device are represented as simple files that can be read and
Details of the individual slave or master design are hidden behind
a consistent interface. The goal is to provide an easy set of tools for a
software designer to create monitoring or control applications. There are
some performance enhancements in the implementation, including data caching,
parallel access to bus masters, and aggregation of device communication.
Still the fundamental goal has been ease of use, flexibility and correctness
rather than speed.
owfs (1) is the filesystem client of the OWFS family of programs.
It runs on linux, freebsd and Mac OS X, and requires the fuse kernel
module and library. (http://fuse.sourceforge.net) which is a user-mode
Essentially, the entire 1-wire bus is mounted to a place in your
filesystem. All the 1-wire devices are accessible using standard file
operations (read, write, directory listing). The system is safe, no actual
files are exposed, these files are virtual. Not all operations are
supported. Specifically, file creation, deletion, linking and renaming are
not allowed. (You can link from outside to a owfs file, but not the other
These options specify the device (bus master) connecting the computer to the
1-wire bus. The 1-wire slaves are connected to the 1-wire bus, and the bus
master connects to a port on the computer and controls the 1-wire bus. The bus
master is either an actual physical device, the kernel w1 module, or an
At least one device option is required. There is no default. More
than one device can be listed, and all will be used. (A logical union unless
you explore the /bus.n/ directories.)
Linux and BSD enforce a security policy restricting access to
hardware ports. You must have sufficient rights to access the given port or
access will silently fail.
port specifies a serial port, e.g. /dev/ttyS0 or an USB port
accessed as serial port, e.g. /dev/ttyUSB0
If OWFS was built with libftdi support, you may be able to
use the ftdi: prefix in any of the options as port to address
a FTDI-based USB device.
For details, see the FTDI ADDRESSING section.
The only supported true USB bus masters are based on the DS2490 chip. The most
common is the DS9490R which has an included 1-wire ID slave with family code
- -d port | --device=port
- DS2480B-based bus master (like the DS9097U or an adapter of the
LINK family in emulation mode). If the adapter doesn't respond, a
passive type (DS9907E or diode/resistor) circuit will be assumed.
- --serial_flextime | --serial_regulartime
Changes details of bus timing (see DS2480B datasheet). Some devices, like
the Swart LCD cannot work with flextime.
- Sets the initial serial port communication speed for all bus masters. Not
all serial devices support all speeds. You can change the individual bus
master speed for a device of the LINK family and DS2880B in
the interface/settings directory. The HA5 speed is set in hardware,
so the command line baud rate should match that rate.
Usually the default settings (9600 for a device of the LINK family
and DS2480B ) and 115200 for the HA5 are sane and shouldn't
- --straight_polarity | --reverse_polarity
- Reverse polarity of the DS2480B output transistors? Not needed for the
DS9097U, but required for some other designs.
- --link=port (LINK)
- iButtonLink LINK adapter (all versions) in non-emulation
mode. Uses an ascii protocol over serial.
This supports the simplified ftdi:<serial number>
- --ha7e=port (HA7E)
- Embedded Data Systems HA7E adapter ( and HA7S ) in
native ascii mode.
- --ha5=port | --ha5=port:a | --ha5=port:acg
- Embedded Data Systems HA5 mutidrop adapter in native ascii
mode. Up to 26 adapters can share the same port, each with an assigned
letter. If no letter specified, the program will scan for the first
response (which may be slow).
- --checksum | --no_checksum (HA5)
Turn on (default) or off the checksum feature of the HA5 communication.
- --passive=port | --ha2=port | --ha3=port |
- Passive 1-wire adapters. Powered off the serial port and using passive
electrical components (resitors and diodes).
- --8bit | --6bit (Passive)
Synthesize the 1-wire waveforme using a 6-bit (default) serial word, or
8-bit word. Not all UART devices support 6 bit operation.
- Timeout (in seconds) for all serial communications. 5 second default. Can
be altered dynamically under /settings/timeout/serial
There are also bus masters based on the serial chip with a USB to
serial conversion built in. These are supported by the serial bus master
I2C is 2 wire protocol used for chip-to-chip communication. The bus masters:
DS2482-100, DS2482-101 and DS2482-800 can specify (via pin
voltages) a subset of addresses on the i2c bus. Those choices are
- -u | --usb
- DS2490 based bus master (like the DS9490R).
- -u2 | --usb=2
- Use the second USB bus master. (The order isn't predicatble, however,
since the operating system does not consistently order USB devices).
- -uall | --usb=ALL
- Use all the USB devices.
- --usb_flextime | --usb_regulartime
- Changes the details of 1-wire waveform timing for certain network
- Willy Robion's alternative USB timing.
- Timeout for USB communications. This has a 5 second default and can be
changed dynamically under /settings/timeout/usb
- 0x1C,0x1D,0x1E,0x1F (DS2482-800 only)
port for i2c masters have the form /dev/i2c-0,
- -d port | --device=port
- This simple form only permits a specific port and the first
- --i2c=port | --i2c=port:i2c_address |
- Specific i2c port and the i2c_address is either the first,
specific, or all or them. The i2c_address is 0,1,2,...
- --i2c | --i2c=: | --i2c=ALL:ALL
- Search the available i2c buses for either the first, the first, or every
The DS2482-800 masters 8 1-wire buses and so will generate
8 /bus.n entries.
These bus masters communicate via the tcp/ip network protocol and so can be
located anywhere on the network. The network_address is of the form
E.g. 192.168.0.1:3000 or localhost:3000
Used for testing and development. No actual hardware is needed. Useful for
separating the hardware development from the rest of the software design.
- LinkHubE network LINK adapter by iButtonLink
- --ha7net=network_address | --ha7net
- HA7Net network 1-wire adapter with specified tcp address or discovered by
udp multicast. By Embedded Data Systems
--timeout_ha7=60 specific timeout for HA7Net communications (60
- Etherweather adapter
- -s network_address | --server=network_address
- Location of an owserver (1) program that talks to the 1-wire bus.
The default port is 4304.
- Timeout for network bus master communications. This has a 1 second default
and can be changed dynamically under /settings/timeout/network
This a linux-specific option for using the operating system's access to bus
masters. Root access is required and the implementation was still in progress
as of owfs v2.7p12 and linux 2.6.30.
- is a list of comma-separated 1-wire devices in the following formats. Note
that a valid CRC8 code is created automatically.
- Hexadecimal family codes (the DS18S20, DS2405 and DS1921 in this
- A more complete hexadecimal unique address. Useful when an actual hardware
device should be simulated.
- The 1-wire device name. (Full ID cannot be speciifed in this format).
- Random address and random values for each read. The device ID is also
random (unless specified).
- --temperature_low=12 --temperature_high=44
- Specify the temperature limits for the fake adapter simulation.
These should be in the same temperature scale that is specified in the
command line. It is possible to change the limits dynamically for each
- Predictable address and predictable values for each read. (See the website
for the algorhythm).
Bus masters are recognized and added dynamically. Details of the
physical bus master are not accessible, bu they include USB, i2c and a
number of GPIO designs on embedded boards.
Access is restrict to superuser due to the netlink broadcast
protocol employed by w1. Multitasking must be configured (threads) on the
FTDI is a brand of USB-to-serial chips which are very common. If your serial
device is connected via a USB serial dongle based on a FTDI chip, or if your
adapter uses a built-in FTDI USB chip (for example, the LinkUSB), you can use
this FTDI addressing.
- Use the linux kernel w1 virtual bus master.
- Timeout for w1 netlink communications. This has a 10 second default and
can be changed dynamically under /settings/timeout/w1
The main benefit with this mode of access is that we can decrease
the communication delay, yielding twice as fast 1-Wire communication in many
The following values for port can be used to identify a
specific FTDI port in several of the serial devices options.
Note that this requires that OWFS is built with libftdi support, which might
not be the case in standard repositories.
- path of bus and device-node (e.g. "003/001") within usb device
tree (usually at /proc/bus/usb/ or /dev/bus/usb/)
- first device with given vendor and product id, ids can be decimal, octal
(preceded by "0") or hex (preceded by "0x")
- as above with index being the number of the device (starting with 0) if
there are more than one
- the device with given vendor id, product id and serial number string
The above formats are parsed fully by libftdi (minus the
An additional format is supported, for certain bus types. This only specifies
the USB serial number.
In order to run owserver (1) without root privileges - as you should, you
must have sufficient permissions to the raw USB node your adapter is connected
to e.g. "003/001" (usually at /proc/bus/usb/ or /dev/bus/usb/).
- ftdi:<serial number>
- Identifies a FTDI device by serial number only. Currently, this is only
valid for the VID/PID found on the LinkUSB (i.e. --link). Note that those
VID/PID's are the default for any FT232R device, and in no way exclusive
An easy way to achieve this would be using chown (1):
- sudo chown :<your user> /dev/bus/usb/003/001
- changes the group of the raw USB node "003/001" from default
"root" to "<your user>"
You can also write a udev (1) rule for your adapter:
Communication in FTDI mode accesses the RAW USB node and NOT the serial USB node
your OS might have created automatically e.g. /dev/ttyUSB0.
- SUBSYSTEM=="usb", DRIVER=="usb",
- saved as a file e.g. "10-FTDI-LinkUSB.rules" in
"/etc/udev/rules.d/", this rule will automate the process of
changing the group to "owsrv" of the raw USB node the LinkUSB
adapter with S/N:AK0048A0 is connected to.
As a side effect, if existing, the serial USB node e.g. /dev/ttyUSB0 is removed
on successful starting of owserver (1). After it's termination un- and
re-plugging the adapter, or un- and reloading of the module ftdi_sio will
recreate the serial USB node.
owusbprobe is THE tool to find the information needed for direct FTDI
However this tool might not yet be packaged in your version. Alternatively you
can also use lsusb to find the usb node your adapter is connected to, and then
use lsusb again on this very node:
- sudo lsusb -D /path/to/your/raw/USB/device/node |egrep
- sudo is necessary to get the value of iSerial field, if the permissions
are still unchanged
Path of a directory to mount the 1-wire file system
- owserver -d ftdi:s:0x0403:0x6001:A800bXHr
- starts owserver with a LinkUSB (VID:0x0403,PID:0x6001,S/N:A800bXHr) as bus
master in DS2480B-based emulation mode with direct FTDI access
- owserver --link=ftdi:A800bXHr
- starts owserver with a LinkUSB (S/N:A800bXHr) as bus master identified by
serial number only in native mode with direct FTDI access
The mountpoint is required. There is no default.
Shorthand for fuse mount option "-o allow_other" Allows uther users to
see the fuse (owfs) mount point and file system. Requires a setting in
/etc/fuse.conf as well.
Sends options to the fuse-mount process. Options should be quoted, e.g. "
Temperature scale used for data output. Celsius is the default.
Can also be changed within the program at
Pressure scale used for data output. Millibar is the default.
Can also be changed within the program at
Choose the representation of the 1-wire unique identifiers. OWFS uses these
identifiers as unique directory names.
Although several display formats are selectable, all must be in
family-id-crc8 form, unlike some other programs and the labelling on
iButtons, which are crc8-id-family form.
Display format for the 1-wire devices. Each device has a 8byte address,
- family code, 1 byte
- ID number, 6 bytes
- CRC checksum, 1 byte
Possible formats are f.i (default, 01.A1B2C3D4E5F6), fi
fic f.ic f.i.c and fi.c
All formats are accepted as input, but the output will be in the
The address elements can be retrieved from a device entry in owfs
by the family, id and crc8 properties, and as a whole with
address. The reversed id and address can be retrieved as r_id
Do we allow writing to the 1-wire bus (writing memory, setting switches, limits,
PIOs)? The write option is available for symmetry, it's the default.
Places the PID -- process ID of owfs into the specified filename. Useful for
startup scripts control.
Whether the program releases the console and runs in the background after
evaluating command line options. background is the default.
- default mixed destination: stderr foreground / syslog background
- syslog only
- stderr only
- /dev/null (quiet mode).
- default errors only
- all high level calls
- data summary for each call
- details level
- debugging chaff
--error_level=9 produces a lot of output
Name of an owfs (5) configuration file with more command line parameters
See also this man page and the web site http://www.owfs.org
Shows basic summary of options.
Version of this program and related libraries.
Timeouts for the bus masters were previously listed in Device options.
Timeouts for the cache affect the time that data stays in memory. Default
values are shown.
Seconds until a volatile property expires in the cache. Volatile
properties are those (like temperature) that change on their own.
- 1-wire bus master options
- cache and communication size and timing
- mountpoint or TCP server settings
- control and debugging options
- Unique ID display format and temperature scale
Can be changed dynamically at
Seconds until a stable property expires in the cache. Stable properties
are those that shouldn't change unless explicitly changed. Memory contents for
Can be changed dynamically at /settings/timeout/stable
Seconds until a directory listing expires in the cache. Directory lists
are the 1-wire devices found on the bus.
Can be changed dynamically at
Seconds until the presence and bus location of a 1-wire device expires in
Can be changed dynamically at
There are also timeouts for specific program responses:
Seconds until the expected response from the owserver (1) is deemed
Can be changed dynamically at /settings/timeout/server
Seconds that an ftp session is kept alive.
Can be changed dynamically at /settings/timeout/ftp
owfs (1) owhttpd (1) owftpd (1) owserver (1) owdir (1) owread (1)
owwrite (1) owpresent (1) owtap (1)
owfs (5) owtap (1) owmon (1)
owtcl (3) owperl (3) owcapi (3)
DS1427 (3) DS1904(3) DS1994 (3) DS2404 (3) DS2404S (3) DS2415 (3) DS2417
DS2401 (3) DS2411 (3) DS1990A (3)
DS1982 (3) DS1985 (3) DS1986 (3) DS1991 (3) DS1992 (3) DS1993 (3) DS1995 (3)
DS1996 (3) DS2430A (3) DS2431 (3) DS2433 (3) DS2502 (3) DS2506 (3) DS28E04 (3)
DS2405 (3) DS2406 (3) DS2408 (3) DS2409 (3) DS2413 (3) DS28EA00 (3)
DS1822 (3) DS1825 (3) DS1820 (3) DS18B20 (3) DS18S20 (3) DS1920 (3) DS1921
(3) DS1821 (3) DS28EA00 (3) DS28E04 (3)
DS2436 (3) DS2437 (3) DS2438 (3) DS2751 (3) DS2755 (3) DS2756 (3) DS2760 (3)
DS2770 (3) DS2780 (3) DS2781 (3) DS2788 (3) DS2784 (3)
Paul Alfille (email@example.com)
- owfs -d /dev/ttyS0 -m /mnt/1wire
- Bus master on serial port
- owfs -F -u -m /mnt/1wire
- USB adapter, temperatures reported in Fahrenheit
- owfs -s 10.0.1.2:4304 -m /mnt/1wire
- Connect to an owserver (1) process that was started on another
machine at tcp port 4304
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