---
name: "OWNet"
section: "3"
platform: "linux"
package: "libownet-perl"
version: "3.2p4+dfsg1-6"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/OWNet"
---

# OWNet(3)

Light weight access to owserver

## NAME

OWNet - Light weight access to **owserver**

## SYNOPSIS

OWNet is an easy way to access **owserver** and thence the 1-wire bus.

Dallas Semiconductor's 1-wire system uses simple wiring and unique addresses for its interesting devices. The **One Wire File System (OWFS)** is a suite of programs that hide 1-wire details behind a file system metaphor. **owserver** connects to the 1-wire bus and provides network access.

**OWNet** is a perl module that connects to **owserver** and allows reading, writing and listing the 1-wire bus.

Example perl program that prints the temperature:

```
 use OWNet ;
 print OWNet::read( "localhost:4304" , "/10.67C6697351FF/temperature" ) ."\n" ;
```

There is the alternative object oriented form:

```
 use OWNet ;
 my $owserver = OWNet->new( "localhost:4304" ) ;
 print $owserver->read( "/10.67C6697351FF/temperature" ) ."\n" ;
```

## SYNTAX

### methods

- **new**

  ```
   my $owserver = OWNet -> new( address ) ;
  ```

- **read**

  ```
   OWNet::read( address, path [,size [,offset]] )
   $owserver -> read( path [,size [,offset]] )
  ```

- **write**

  ```
   OWNet::write( address, path, value [,offset] )
   $owserver -> write( path, value [,offset] )
  ```

- **dir**

  ```
   OWNet::dir( address, path )
   $owserver -> dir( path )
  ```

### *address*

TCP/IP *address* of **owserver**. Valid forms:

- *name* test.owfs.net:4304

  - *quad* number: 123.231.312.213:4304

  - *host* localhost:4304

  - *port* 4304

  ### *additional arguments*

Additional arguments to add to address

Temperature scale can also be specified in the *address*. Same syntax as the other OWFS programs:

- \-C Celsius (Centigrade)

  - \-F Fahrenheit

  - \-K Kelvin

  - \-R Rankine

  Pressure scale can also be specified in the *address*. Same syntax as the other OWFS programs:

- \--mbar millibar (default)

  - \--atm atmosphere

  - \--mmHg mm Mercury

  - \--inHg inch Mercury

  - \--psi pounds per inch^2

  - \--Pa pascal

  Device display format (1-wire unique address) can also be specified in the *address*, with the general form of -ff\[.\]i\[\[.\]c\] (*f*amily *i*d *c*rc):

- \-ff.i /10.67C6697351FF (default)

  - \-ffi /1067C6697351FF

  - \-ff.i.c /10.67C6697351FF.8D

  - \-ff.ic /10.67C6697351FF8D

  - \-ffi.c /1067C6697351FF.8D

  - \-ffic /1067C6697351FF8D

  Show directories that are themselves directories with a '/' suffix ( e.g. /10.67C6697351FF/ )

- \-slash show directory elements

  Warning messages will only be displayed if verbose flag is specified in *address*

- \-v verbose

  ### *path*

**owfs**-type *path* to an item on the 1-wire bus. Valid forms:

- main directories

  Used for the *dir* method. E.g. "/" "/uncached" "/1F.321432320000/main"

- device directory

  Used for the *dir* and *present* method. E.g. "/10.4300AC220000" "/statistics"

- device properties

  Used to *read*, *write*. E.g. "/10.4300AC220000/temperature"

### *value*

New *value* for a device property. Used by *write*.

## METHODS

- **new**

  Object-oriented (only):

  **OWNet::new**( *address* )

  Create a new OWNet object -- corresponds to an **owserver**.

  Error (and undef return value) if:

  - 1 Badly formed tcp/ip *address*

    - 2 No **owserver** at *address*

    -

    - **read**

  - Non object-oriented:

    **OWNet::read**( *address* , *path* \[ , *size* \[ , *offset* \] \] )

  - Object-oriented:

    `$ownet`-\>**read**( *path* \[ , *size* \[ , *offset* \] \] )

  Read the value of a 1-wire device property. Returns the (scalar string) value of the property.

  *size* (number of bytes to read) is optional

  *offset* (number of bytes from start of field to start write) is optional

  Error (and undef return value) if:

  - 1 (Non object) No **owserver** at *address*

    - 2 (Object form) Not called with a valid OWNet object

    - 3 Bad *path*

    - 4 *path* not a readable device property

    -

    - **write**

  - Non object-oriented:

    **OWNet::write**( *address* , *path* , *value* \[ , *offset* \] )

  - Object-oriented:

    `$ownet`-\>**write**( *path* , *value* \[ , *offset* \] )

  Set the value of a 1-wire device property. Returns "1" on success.

  *offset* (number of bytes from start of field to start write) is optional

  Error (and undef return value) if:

  - 1 (Non object) No **owserver** at *address*

    - 2 (Object form) Not called with a valid OWNet object

    - 3 Bad *path*

    - 4 *path* not a writable device property

    - 5 *value* incorrect size or format

    -

    - **dir**

  - Non object-oriented:

    **OWNet::dir**( *address* , *path* )

  - Object-oriented:

    `$ownet`-\>**dir**( *path* )

  Return a comma-separated list of the entries in *path*. Entries are equivalent to "fully qualified names" -- full path names.

  Error (and undef return value) if:

  - 1 (Non object) No **owserver** at *address*

    - 2 (Object form) Not called with a valid OWNet object

    - 3 Bad *path*

    - 4 *path* not a directory

    -

    - **present** (deprecated)

  - Non object-oriented:

    **OWNet::present**( *address* , *path* )

  - Object-oriented:

    `$ownet`-\>**present**( *path* )

  Test if a 1-wire device exists.

  Error (and undef return value) if:

  - 1 (Non object) No **owserver** at *address*

    - 2 (Object form) Not called with a valid OWNet object

    - 3 Bad *path*

    - 4 *path* not a device

    -

    ## DESCRIPTION

### OWFS

*OWFS* is a suite of programs that allows easy access to *Dallas Semiconductor*'s 1-wire bus and devices.  *OWFS* provides a consistent naming scheme, safe multplexing of 1-wire traffice, multiple methods of access and display, and network access.  The basic *OWFS* metaphor is a file-system, with the bus beinng the root directory, each device a subdirectory, and the the device properties (e.g. voltage, temperature, memory) a file.

### 1-Wire

*1-wire* is a protocol allowing simple connection of inexpensive devices.  Each device has a unique ID number (used in its OWFS address) and is individually addressable.  The bus itself is extremely simple -- a data line and a ground. The data line also provides power.  1-wire devices come in a variety of packages -- chips, commercial boxes, and iButtons (stainless steel cans).  1-wire devices have a variety of capabilities, from simple ID to complex voltage, temperature, current measurements, memory, and switch control.

### Programs

Connection to the 1-wire bus is either done by bit-banging a digital pin on the processor, or by using a bus master -- USB, serial, i2c, parallel.  The heavy-weight *OWFS* programs: **owserver** **owfs** **owhttpd** **owftpd** and the heavy-weight perl module **OW** all link in the full *OWFS* library and can connect directly to the bus master(s) and/or to **owserver**.

**OWNet** is a light-weight module. It connects only to an **owserver**, does not link in the *OWFS* library, and should be more portable..

### Object-oriented

**OWNet** can be used in either a classical (non-object-oriented) manner, or with objects.  The object stored the ip address of the **owserver** and a network socket to communicate.  **OWNet** will use persistent tcp connections for the object form -- potentially a performance boost over a slow network.

## EXAMPLES

### owserver

**owserver** is a separate process that must be accessible on the network. It allows multiple clients, and can connect to many physical 1-wire adapters and 1-wire devices. It's address must be discoverable -- either set on the command line, or at it's default location, or by using Bonjour (zeroconf) service discovery.

An example owserver invocation for a serial adapter and explicitly chooses the default port:

```
 owserver -d /dev/ttyS0 -p 4304
```

### OWNet

```
 use OWNet ;
 # Create owserver object
 my $owserver = OWNet->new('localhost:4304 -v -F') ; #default location, verbose errors, Fahrenheit degrees
 # my $owserver = OWNet->new() ; #simpler, again default location, no error messages, default Celsius
 #print directory
 print $owserver->dir('/') ;
 #print temperature from known device (DS18S20,  ID: 10.13224366A280)
 print "Temperature: ".$owserver->read('/uncached/10.13224366A280/temperature') ;
 # Now for some fun -- a tree of everything:
 sub Tree($$) {
   my $ow = shift ;
   my $path = shift ;
   print "$path\t" ;
   # first try to read
   my $value = $ow->read($path) ;
   if ( defined($value) ) {
     print "$value\n";
     return ;
   }
   # not readable, try as directory
   my $dirstring = $ow->dir($path) ;
   if ( defined($dirstring) ) {
     print "<directory>\n" ;
     my @dir = split /,/ ,  $ow->dir($path) ;
     foreach (@dir) {
        Tree($ow,$_) ;
     }
     return ;
   }
   # can't read, not directory
   print "<write-only>\n" ;
   return ;
 }
 Tree( $owserver, '/' ) ;
```

## INTERNALS

### Object properties (All private)

- ADDR

  literal sting for the IP address, in dotted-quad or host format. This property is also used to indicate a substantiated object.

- PORT

  string for the port number (or service name). Service name must be specified as :owserver or the like.

- SG

  Flag sent to server, and returned, that encodes temperature scale and display format. Persistence is also encoded in this word in the actual tcp message, but kept separately in the object.

- VERBOSE

  Print error messages? Set by "-v" in object invocation.

- SLASH

  Add "/" to the end of directory entries. Set by "-slash" in object invocation.

- SOCK

  Socket address (object) for communication. Stays defined for persistent connections, else deleted between calls.

- PERSIST

  State of socket connection (persistent means the same socket is used which speeds network communication).

- VER

  owprotocol version number (currently 0)

### Private methods

- \_self

  Takes either the implicit object reference (if called on an object) or the ip address in non-object format.  In either case a socket is created, the persistence bit is properly set, and the address parsed.  Returns the object reference, or undef on error.  Called by each external method (read,write,dir) on the first parameter.

- \_new

  Takes command line invocation parameters (for an object or not) and properly parses and sets up the properties in a hash array.

- \_Sock

  Socket processing, including tests for persistence and opening. If no host is specified, localhost (127.0.0.1) is used. If no port is specified, uses the IANA allocated well known port (4304) for owserver. First looks in /etc/services, then just tries 4304.

- \_ToServer

  Sends a message to owserver. Formats in owserver protocol. If a persistent socket fails, retries after new socket created.

- \_FromServerBinaryParse

  Reads a specified length from server

- \_FromServer

  Reads whole packet from server, using \_FromServerBinaryParse (first for header, then payload). Discards ping packets silently.

- \_BonjourLookup

  Uses the mDNS service discovery protocol to find an available owserver. Employs NET::Rendezvous (an earlier name or Apple's Bonjour) This module is loaded only if available. (Uses the method of http://sial.org/blog/2006/12/optional\_perl\_module\_loading.html)

## AUTHOR

Paul H Alfille paul.alfille@gmail.com

## BUGS

Support for proper timeout using the "select" function seems broken in perl. This might leave the routines vulnerable to network timing errors.

## SEE ALSO

- http://www.owfs.org

  Documentation for the full **owfs** program suite, including man pages for each of the supported 1-wire devices, and more extensive explanatation of owfs components.

- http://owfs.sourceforge.net/projects/owfs

  Location where source code is hosted.

## COPYRIGHT

Copyright (c) 2007 Paul H Alfille. All rights reserved.\
  This program is free software; you can redistribute it and/or\
  modify it under the same terms as Perl itself.