A protocol tag is destined to read/write data from/to a controller. A tag is added, using the context menu of a device/group.
There are the following main settings of a tag in the IEC61850 protocol:
•Functional constraint - a section parameters belong to. The full table is given below.
•Data type MMS - a MMS data type of parameters polled.
•Identifier - an identifier of a variable in a device.
Functional constraint |
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Constraint |
Description |
Access type* |
ST |
Status Information |
ReadOnly |
MX |
Measurands (Analog Values) |
ReadOnly |
CO |
Control |
ReadWrite |
SP |
Set Point |
ReadWrite |
SV |
Substitution |
ReadWrite |
CF |
Configuration |
ReadWrite |
DC |
Description |
ReadWrite |
SG |
Setting Group |
ReadOnly |
SE |
Setting Group Editable |
ReadWrite |
EX |
Extended Definition |
ReadOnly |
BR |
Buffered Report |
ReadWrite |
RP |
Unbuffered Report |
ReadWrite |
LG |
Logging |
ReadWrite |
MS |
Multi-cast Sampled Value Control |
ReadWrite |
US |
Uni-cast Sampled Value Control |
ReadWrite |
• DataSet name - if the device supports built-in datasets (DataSet), and the device enables "Use DataSet", then specifying the name of the data set indicates that this parameter is included in this DataSet. In this case, the tag is excluded from the general periodic poll. When importing tags, the setting is imported from the device.
•Report control block name - if the device supports reports (Report) and the device has "Use Reports" enabled, then specifying the name of the report indicates that this parameter applies to this report. In this case, the tag is excluded from the general periodic poll. When importing tags, the setting is imported from the device.
•Access type - by default, all tags in the OPC server has the ReadOnly access type. For all of tags, the ReadWrite access type can be set (including tags of the functional constraint that does not support writing) When attempting to write to such tags, the device returns an error.
•Quality Identifier - this field indicates the identifier of the device variable, according to the value of which the tag quality indicator is formed. The formation of a sign of quality occurs according to the following table described in the device section.
•Timestamp Identifier - this field indicates the identifier of the device variable, according to the value of which the tag time stamp is formed.