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Figure 8

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4.5. Publications of Values
The Web User may require the current value of a particular data attribute maintained
by an IEC 61850 Server. To enable each value received to be properly decoded by the
receiving entity, the relevant data attribute type must be known; the previous section
provides a detailed description of the services defined to allow the Web User to acquire
information about the data type.
The Web User may need to request only the current value of a particular data attribute, or
he may require receipt of updates of the value over time. For this reason, a particular service
was defined to allow the Web User to retrieve the current value of a particular data attribute;
moreover, the service may allow the Web User to request the automatic sampling of the data
attribute and the transmissions of the sampled values with the same sampling frequency.
To use this service, the Web User sends a POST request to a particular Web Service Interface
of the IEC 61850 Web Platform, containing three fields: identifier, interval, and broker.
Identifier contains the details about the data attribute whose value the Web User is
interested in. It was assumed that the identifier is given according to the same formalism
described in Section
4.1
. For example, considering the example shown by Figure
3
, the iden-
tifier “BCU1M19/C1/LBAYMMXU1/A/phsB/cVal/mag/f”, refers to the data attribute
belonging to the Basic Data Attribute with the name = “f”. The operator & may be used in
the POST request to specify a list of variables.
The interval field is used by the Web User to specify the desired sampling interval
of the specified data attribute, in milliseconds; the sampling interval corresponds to the
interval with which the IEC 61850 Client reads the requested data attribute from the server,
and the relevant value is given back to the Web User through MQTT frames. If the Web
User requires only one value (i.e., the current one), the interval must be set to “0”.
The information about the Broker is passed by the Web User if he needs to receive
the requested value(s) on a specific Broker; otherwise, a default Broker is used by the IEC
61850 Web Platform.
Figure
9
shows an example of the service explained above. It is assumed that the Web User
needs to receive the values of the BDA “BCU1M19/C1/LBAYMMXU1/A/phsB/cVal/mag/f”,
sampled every 500 ms.
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receiving entity, the relevant data attribute
type must be known; the previous section pro-
vides a detailed description of the services defined to allow the Web User to acquire in-
formation about the data type.
The Web User may need to request only the current value of a particular data attrib-
ute, or he may require receipt of updates of the value over time.
For this reason, a partic-
ular service was defined to allow the Web User to retrieve the current value of a particular
data attribute; moreover, the service may allow the Web User to request the automatic
sampling of the data attribute and the transmissions of the sampled values with the same
sampling frequency.
To
use this service, the Web User sends a POST request to a particular Web Service
Interface of the IEC 61850 Web Platform, containing three fields: identifier, interval, and
broker.
Identifier contains the details about the data attribute
whose value the Web User is
interested in. It was assumed that the identifier is given according to the same formalism
described in Section 4.1. For example, considering the example shown by Figure 3, the
identifier “BCU1M19/C1/LBAYMMXU1/A/phsB/cVal/mag/f”, refers to the data attribute
belonging to the Basic Data Attribute with the name = “f”. The operator & may be used in
the POST request to specify a list of variables.
The interval field is used by the Web User to specify the desired
sampling interval of
the specified data attribute, in milliseconds; the sampling interval corresponds to the in-
terval with which the IEC 61850 Client reads the requested data attribute from the server,
and the relevant value is given back to the Web User through MQTT frames.
If the Web
User requires only one value (i.e., the current one), the interval must be set to “0”.
The information about the Broker is passed by the Web User if he needs to receive
the requested value(s) on a specific Broker; otherwise, a default
Broker is used by the IEC
61850 Web Platform.
Figure 9 shows an example of the service explained above. It is assumed that the Web
User needs to receive the values of the BDA “BCU1M19/C1/LBAY-
MMXU1/A/phsB/cVal/mag/f”, sampled every 500 ms.