Add data access items to dagroup
object
IObj = additem(GObj,'IName')
IObj = additem(GObj,'IName','DataType
')
IObj = additem (GObj,'IName','DataType
','Active
')
IObj = additem(GObj,'IName')
adds items to
the group object GObj
with fully qualified item IDs given by
IName
. The object IObj
is the created item
object or objects. You specify IName
as a single item ID or as a
cell array of item IDs.
The daitem
object provides a connection to a data variable in
the physical device and returns information about the data variable, such as its
value, quality, and time stamp. Note that you cannot add a given item to the same
group more than once. However, you can add the same item to different groups.
By default, IObj
is active; that is, if the group’s Subscription
property is on
, the item's Value
, Quality
, and TimeStamp
properties will be updated at the group's UpdateRate
.
Servers often require item IDs to be specified in the correct case. You can use
the serveritems
function to find valid item
IDs.
Note
You cannot add items to a public group. A public group has a fixed set of item
IDs common to all clients sharing that group. The GroupType
property of a dagroup
object indicates the type of
group.
IObj = additem(GObj,'IName','
adds items to the group object DataType
')GObj
with the requested data type
given by
'
DataType
'
. You
specify '
DataType
'
as a cell array of character vectors, one for each item ID.
'
DataType
'
is
the data type in which the item's value will be stored in the MATLAB® workspace. The supported data types are 'logical'
,
'int8'
, 'uint8'
,
'int16'
, 'uint16'
,
'int32'
, 'uint32'
,
'single'
, 'double'
,
'char'
, and 'date'
. Note that if the
requested data type is rejected by the server, the item is not added. The requested
data type is stored in the DataType
property. The canonical data
type (the data type used by the server to store the item value) is stored in the
CanonicalDataType
property.
IObj = additem (GObj,'IName','
adds items to the group object DataType
','Active
')GObj
with active status given by
'
Active
'
. You
specify '
Active
'
as
a cell array of character vectors, one for each item ID.
'
Active
'
can be
'on'
or 'off'
. The active status is stored
in the Active
property.
Create a client and a group.
da = opcda('localhost','Matrikon.OPC.Simulation'); connect(da); grp = addgroup(da,'ExAddItem');
Add two items with their canonical data types.
itm = additem(grp, {'Random.Real4','Random.Real8'})
Add an item with a 'double'
data type.
itmDbl = additem(grp,'Random.Int2','double')
Add an inactive item.
itmInact = additem(grp,'Random.UInt4','double','off')