User Manual

Table Of Contents
SARA-R4 series-AT commands manual
UBX-17003787 - R16
26Lightweight M2M
Page 311 of 401
26Lightweight M2M
26.1LwM2M Objects management
26.1.1Introduction
26.1.1.1SARA-R4 object management
Lightweight M2M is a protocol from the Open Mobile Alliance (OMA) that defines the application layer
communication between a LwM2M server and a LwM2M client. LwM2M includes device management and
service enablement for LwM2M devices. For more details on LwM2M protocol, see Lightweight Machine to
Machine Technical Specification [133].
LwM2M objects implemented as Lua scripts act as the container for the objects, object instances, and
resources.
u-blox cellular modules allows adding, removing or querying an object from the LwM2M object table of available
objects with these AT commands:
+ULWM2MADD dynamically adds an object, that has been previously copied to the device file system, to the
LwM2M object table. An object must be added to the LwM2M object table before create or delete operations
can be performed. The LwM2M object shall be downloaded by means of file system AT commands with the
"XLWM2M" tag, for more details see File tags.
+ULWM2MREMOVE dynamically removes an object from the LwM2M object table, along with any existing
instances. The object file on the device file system is not removed. An object that has been removed from
the LwM2M object table cannot have a create operation performed.
+ULWM2MLIST lists the object ID and the object instances of a specific LwM2M object. The command
allows also to list the object IDs of all objects and object instances in the LwM2M object table. An object
that does not appear listed by +ULWM2MLIST must be added before create operations can be performed.
All the LwM2M objects, that stored in the MT as Lua scripts with "XLWM2M" tag, are automatically added
to the LwM2M object table during LwM2M client initialization at device power up.
LwM2M object table is empty by factory-programmed setting.
Additional object files may be added by means of file system AT commands with the "XLWM2M" tag, for more
details see File tags.
It is possible to modify LwM2M objects that have already been added to the LwM2M object table, using the
following AT commands:
+ULWM2MCREATE creates an object instance associated with a given server ID. The object must already
be added to the LwM2M object table (see +ULWM2MADD AT command).
+ULWM2MDELETE deletes an object instance. The delete target must already exist and be listed by the
+ULWM2MLIST AT command.
+ULWM2MWRITE writes to an object instance or resource. The instance must already exist and be listed
by the +ULWM2MLIST AT command. Otherwise, it must be added with +ULWM2MLIST before writing.
+ULWM2MREAD reads an object, object instance, or resource. The read target must already exist and be
listed by the +ULWM2MLIST AT command.
SARA-R4
For the +ULWM2MADD, +ULWM2MREMOVE, +ULWM2MLIST, +ULWM2MCREATE, +ULWM2MWRITE,
+ULWM2MREAD AT commands the maximum length of the command line and the maximum length of
the information text response is 1040 characters.