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Protocol translation
Pivot
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object definition
Before diving into the details of the specification, it is useful to illustrate some use cases. They should help demonstrate how the specification is expected to be used and to help understand the benefits of a pivot formatobject.
The objective of a gateway is to allow communication between different systems by providing some translation mechanisms from one means of communication to another one.
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In this use case, monitoring data are acquired from a field device called RTU (Remote Terminal Unit) which acts as a IEC 104 server (slave) and are exposed to the central SCADA which acts as a ICCP TASE.2 client. Each incoming message from the RTU comes as an IEC 104 ASDU object. The south service plugin applies a first translation process which consists of (1) reading and checking the ASDU object using the IEC 104 data model and (2) mapping each data attribute to the corresponding pivot format object data attribute. Once the message is converted to a pivot format object, it can then be stored or consumed by the north or any other service. The north service plugin can then apply a second translation process which consists of (3) reading and checking the pivot format object using the pivot format data model and (4) mapping each data attribute to the corresponding TASE.2 data attribute. The resulting TASE.2 object can then be exposed to the TASE.2 client by the north service plugin.
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Monitoring data are acquired from a field device called IED (Intelligent Electronic Device) which acts as a 61850 MMS server and are exposed to the central SCADA which acts as a OPC UA client. Each incoming message from the IED comes as a 61850 MMS object. The south service plugin applies a first translation process which consists of (1) reading and checking the 61850 MMS object using the 61850 MMS data model and (2) mapping each data attribute to the corresponding pivot format object data attribute. Once the message is converted to a pivot format object, it can then be stored or consumed by the north or any other service. The north service plugin can then apply a second translation process which consists of (3) reading and checking the pivot format object using the pivot format object data model and (4) mapping each data attribute to the corresponding OPC UA data attribute. The resulting OPC UA object can then be exposed to the OPC UA client by the north service plugin.
Control data are received from the control center SCADA which acts as a OPC UA client and are sent to the IED which acts as a 61850 server. Each incoming message from the control center SCADA comes as an OPC UA object. The north service plugin applies a first translation process which consists of (1) reading and checking the OPC UA object using the OPC UA data model and (2) mapping each data attribute to the corresponding pivot format object data attribute. Once the message is converted to a pivot format object, it can then be stored or consumed by the south or any other service. The south service plugin can then apply a second translation process which consists of (3) reading and checking the pivot format object using the pivot format object data model and (4) mapping each data attribute to the corresponding 61850 MMS data attribute. The resulting 61850 MMS object can then be exposed to the 61850 client by the south service plugin.
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In this alternative scenario, the gateway is connected to multiple SCADAs using two different protocols. The North plugin (TASE.2) exposes data to the TASE.2 SCADA and the North plugin OPC UA exposes data to the OPC UA SCADA. Instead of having a one to one translation process (61850 to TASE.2, 61850 to OPC UA, TASE.2 to 61850, OPC UA to 61850), we use the pivot format object to transmit data from 61850 to both TASE.2 and OPC UA. The translation process is done only once for each protocol.
Benefits and challenges of a pivot
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object
Benefits
The main benefit of the pivot format object is it allows decoupling the protocols data model from each other. Each south or north plugin deals with the complexity and the specifics of a given protocol without interfering with the core of the gateway or with another south/north plugin. Adding new protocol plugins or maintaining existing ones is then made much easier. This contributes in maintaining the whole gateway system at a low level of complexity thus minimizing the costs of new developments or maintenance.
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In order to reach the goal of simplicity we want to achieve, the main challenge is to be able to build a pivot format object that is technically independent from the protocols. The data model should also be neutral regarding protocols data models. The protocol translation should not imply a loss or degradation of the source information, especially in the case where the input and output protocols are identical.
Pivot
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object design proposition
| Code Block | ||||
|---|---|---|---|---|
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{
"data_object_header":{
"doh_type":"some_value",
"doh_name":"some_value",
"doh_ca":"some_value",
"doh_oa":"some_value",
"doh_cot":"some_value",
"doh_test":"some_value",
"doh_negative":"some_value",
"doh_version":"some_value",
"doh_src_prot":"some_value"
},
"data_object_item":{
"doi_ioa":"some_value",
"doi_value":"some_value",
"doi_qual_class":"some_value",
"doi_quality":"some_value",
"doi_current_src":"some_value",
"doi_normal_src":"some_value",
"doi_normal_value":"some_value",
"doi_ts_class":"some_value",
"doi_ts":"some_value",
"doi_ts_qual":"some_value",
"doi_ts_sum_time":"some_value",
"doi_ts_subs":"some_value",
"doi_cov_class":"some_value",
"doi_cov_counter":"some_value"
}
} |
The pivot format object uses JSON with a header and item structure.
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| Code Block | ||
|---|---|---|
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{
"exchanged_data":{
"name":"iec104client",
"version":"1.0",
"asdu_list":[
{
"ca":41025,
"type_id":"M_ME_NA_1",
"label":"TM-1",
"ioa":4202832
},
{
"ca":41025,
"type_id":"M_ME_NA_1",
"label":"TM-2",
"ioa":4202852
},
{
"ca":41025,
"type_id":"M_SP_TB_1",
"label":"TS-1",
"ioa":4206948
}
]
}
} |
IEC 104 to pivot
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object translation
IEC 104 ASDU data model
Reference: NF EN 60870-5-101 § 7.3.1.22
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INFORMATION OBJECT ADDRESS
SIQ
CP56Time2a
IEC 104 to pivot
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object conversion configuration model
| Code Block | ||
|---|---|---|
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{
"protocol_translation":{
"name":"iec104_to_pivot",
"version":"1.0",
"mapping":{
"data_object_header":{
"doh_type":"type_id",
"doh_name":"internal_id",
"doh_ca":"ca",
"doh_oa":"oa",
"doh_cot":"cot",
"doh_test":"istest",
"doh_negative":"isnegative"
},
"data_object_item":{
"doi_ioa":"ioa",
"doi_value":"value",
"doi_quality":"quality_desc",
"doi_ts":"time_marker",
"doi_ts_qual":"isinvalid",
"doi_ts_sum_time":"isSummerTime"
}
}
}
} |
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NB: The conversion process shall produce as many pivot format objects as information objects in the source ASDU.
Pivot
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resulting object
| Code Block | ||
|---|---|---|
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{
"data_object_header":{
"doh_type":"some_value",
"doh_name":"not_populated",
"doh_ca":"some_value",
"doh_oa":"some_value",
"doh_cot":"some_value",
"doh_test":"some_value",
"doh_negative":"some_value",
"doh_version":"some_value",
"doh_src_prot":"some_value"
},
"data_object_item":{
"doi_ioa":"some_value",
"doi_value":"some_value",
"doi_qual_class":"not_populated",
"doi_quality":"some_value",
"doi_current_src":"not_populated",
"doi_normal_src":"not_populated",
"doi_normal_value":"not_populated",
"doi_ts_class":"not_populated",
"doi_ts":"some_value",
"doi_ts_qual":"some_value",
"doi_ts_sum_time":"some_value",
"doi_ts_subs":"some_value",
"doi_cov_class":"not_populated",
"doi_cov_counter":"not_populated"
}
} |
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| Code Block | ||
|---|---|---|
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{
"protocol_stack": {
"name": "iec104server",
"version": "1.0",
"transport_layer": {
"bind_on_ip": "FALSE",
"port": 2404,
"tsecurity": "NONE",
"k_value": 12,
"w_value": 8,
"t1_timeout": 15,
"t2_timeout": 10,
"t3_timeout": 20,
"open_new_path": "TRUE",
"bind_on_active": "FALSE",
"disc_on_iframe": "TRUE"
},
"application_layer": {
"orig_size": 1,
"orig_addr": "0",
"ca_asdu_size": 2,
"ioaddr_size": 3,
"struct_addr": "FALSE",
"asdu_size": 0,
"default_class": "CLASS1",
"time_sync": "FALSE",
"comm_exec_timeout": 20000,
"comm_recv_timeout": 5000,
"auto_comm_actcon": "FALSE",
"auto_comm_actterm": "TRUE",
"cmd_block_sel": "FALSE",
"abs_time": "TRUE",
"tzsource": "OS",
"set_wday": "TRUE",
"tsiv": "IGNORE",
"spon_in_passive": "TRUE",
"reset": "TRUE",
"filter_orig": "FALSE",
"lifeact": "TRUE",
"startup": "FALSE",
"active": "TRUE"
}
}
} |
Pivot
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object to IEC 104 translation
Pivot
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object to IEC 104 conversion configuration model
| Code Block | ||
|---|---|---|
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{
"protocol_translation":{
"name":"pivot_to_iec104",
"version":"1.0",
"mapping":{
"data_object_header":{
"type_id":"doh_type",
"ca":"doh_ca",
"oa":"doh_oa",
"cot":"doh_cot",
"istest":"doh_test",
"isnegative":"doh_negative"
},
"data_object_item":{
"ioa":"doi_ioa",
"value":"doi_value",
"quality_desc":"doi_quality",
"time_marker":"doi_ts",
"isinvalid":"doi_ts_qual",
"isSummerTime":"doi_ts_sum_time",
"isSubstituted":"doi_ts_subs"
}
}
}
} |
Conversion process
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IEC 104 ASDU resulting object
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ICCP TASE.2 exchanged data points configuration
<not yet designed>
ICCP TASE.2 to pivot
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object translation
DataValue Indication Point data model
PointName
PointType
PointRealValue
PointStateValue
PointDiscreteValue
QualityClass
Validity
CurrentSource
NormalSource
NormalValue
TimeStampClass
TimeStamp
TimeStamp Quality
COVClass
COVCounter
ICCP TASE.2 to pivot
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object conversion configuration model
| Code Block | ||
|---|---|---|
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{
"protocol_translation":{
"name":"tase2_to_pivot",
"version":"1.0",
"mapping":{
"data_object_header":{
"doh_type":"PointType",
"doh_name":"PointName"
},
"data_object_item":{
"doi_value":"PointRealValue", //PointStateValue or PointDiscreteValue
"doi_qual_class":"QualityClass",
"doi_quality":"Validity",
"doi_current_src":"CurrentSource",
"doi_normal_src":"NormalSource",
"doi_normal_value":"NormalValue",
"doi_ts_class":"TimeStampClass",
"doi_ts":"TimeStamp",
"doi_ts_qual":"TimeStamp Quality",
"doi_cov_class":"COVClass",
"doi_cov_counter":"COVCounter"
}
}
}
} |
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Pivot
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object resulting object
| Code Block | ||
|---|---|---|
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{
"data_object_header":{
"doh_type":"some_value",
"doh_name":"some_value",
"doh_ca":"not_populated",
"doh_oa":"not_populated",
"doh_cot":"not_populated",
"doh_test":"not_populated",
"doh_negative":"not_populated",
"doh_version":"some_value",
"doh_src_prot":"some_value"
},
"data_object_item":{
"doi_ioa":"not_populated",
"doi_value":"some_value",
"doi_qual_class":"some_value",
"doi_quality":"some_value",
"doi_current_src":"some_value",
"doi_normal_src":"some_value",
"doi_normal_value":"some_value",
"doi_ts_class":"some_value",
"doi_ts":"some_value",
"doi_ts_qual":"some_value",
"doi_ts_sum_time":"not_populated",
"doi_ts_subs":"not_populated",
"doi_cov_class":"some_value",
"doi_cov_counter":"some_value"
}
} |
Pivot
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object to ICCP TASE.2 translation
Pivot
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object to ICCP TASE.2 conversion configuration model
| Code Block | ||
|---|---|---|
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{
"protocol_translation":{
"name":"pivot_to_tase2",
"version":"1.0",
"mapping":{
"data_object_header":{
"PointType":"doh_type",
"PointName":"doh_name"
},
"data_object_item":{
"PointRealValue": "doi_value", //PointStateValue or PointDiscreteValue
"QualityClass":"doi_qual_class",
"Validity":"doi_quality",
"CurrentSource":"doi_current_src",
"NormalSource":"doi_normal_src",
"NormalValue":"doi_normal_value",
"TimeStampClass":"doi_ts_class",
"TimeStamp":"doi_ts",
"TimeStamp Quality":"doi_ts_qual",
"COVClass":"doi_cov_class",
"COVCounter":"doi_cov_counter"
}
}
}
} |
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