Contents
Introduction
All data points available trough DBPC are represented by a Tag object. Those objects are available trough DBUS thanks to a DBPC server.
This part describe standard DBPC Tag class models.
There is a basic class called Tag. all Tag class corresponding to data points value are inherited from this basic class
Basic Tag class
Properties
STRING name
This string stores the name of the tag. This name is unique for dbpc-server instance and refers the tag item.
STRING address
This string store where the value can be retried by the DBPC server. It format is specific to the protocol implemented by the DBPC server.
DOUBLE timestamps
This property store the late time when the value has been updated. Generally timestamps is set by the server itself according to system clock. Depending on the protocol implemented, this value can also come directly from the device. If communication time are not predictable, timestamps must be set when the update request is send to the Device. So the stored timestamps is always earlier than the real timestamps.
DOUBLE validity
This property stores the validity of the value. Validity is given in seconds. On client read request, according to timestamps and validity, outdated value are updated.
INT update_mode
correspond to update mode : 1 = continuous, 2 = on use.
INT permission
What permissions does DBPC have to this value: 0-READ, 1-WRITE, 2-READ/WRITE
INT user_permissions
This need more research. Dbus seems to provide security functionality.
INT value_type
The data_type stored by the tag. It can be:
- - BIT - BYTE - WORD - DWORD - INT - DINT - REAL
INT value_size
The number of elements of #value_type stored in #value. This is valid for arrays of values.
VOID value
The value of the tag, according to the data type defined.
Methods
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Events
data_change
In continuous mode, this event append when value change
Bool item class
Properties
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Methods
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Events
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