LWM2M

LightweightM2M is a device management protocol designed for sensor networks and the demands of a machine-to-machine (M2M) environment. With LwM2M, OMA SpecWorks has responded to demand in the market for a common standard for managing lightweight and low power devices on a variety of networks necessary to realize the potential of IoT. The LwM2M protocol, designed for remote management of M2M devices and related service enablement, features a modern architectural design based on REST, defines an extensible resource and data model and builds on an efficient secure data transfer standard called the Constrained Application Protocol (CoAP).

An object covers a certain use case whilst its resources provide more details in information and functionality. For now OMA is reserving different scopes for different uses:

Category	Object ID Range	Description
oma-label	0 – 1023	Objects defined by the Open Mobile Alliance
reserved	1024 – 2047	Reserved for future use
ext-label	2048 – 10240	Objects defined by a 3rd party SDO
x-label	10241 – 32768	Objects defined by a vendor or individual. Such an object may be either private (no DDF or Specification made available) or public. These objects are optionally private. This is indicated at the time of submission

The higher numbers are open to custom usage, which comes in handy if the functionality, that is needed to model, is not there, yet. For a more detailed list of yet used object IDs, click here

This guide will concentrate on the Object-ID 3 which represents the Device itself. It has 17 resources that split up as follows.

Id	Name	Type	Operations	Multiple Instances	Mandatory
0	Manufacturer	String	Read	Single	Optional
1	Model Number	String	Read	Single	Optional
2	Serial Number	String	Read	Single	Optional
3	Firmware Version	String	Read	Single	Optional
4	Reboot	–	Execute	Single	Mandatory
5	Factory Reset	–	Execute	Single	Optional
6	Available Power	Integer	Read	Multiple	Optional
7	Power Source Voltage	Integer	Read	Multiple	Optional
8	Power Source Current	Integer	Read	Multiple	Optional
9	Battery Level	Integer	Read	Single	Optional
10	Memory Free	Integer	Read	Single	Optional
11	Error Code	Integer	Read	Multiple	Mandatory
12	Reset Error Code	–	Execute	Single	Optional
13	Current Time	Time	Read, Write	Single	Optional
14	UTC Offset	String	Read, Write	Single	Optional
15	Timezone	String	Read, Write	Single	Optional
16	Supported Binding and Modes	String	Read	Single	Mandatory