IEC 61158-6-2:2023

IEC 61158-6-2 ®
Edition 5.0 2023-03
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 6-2: Application layer protocol specification – Type 2 elements

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IEC 61158-6-2 ®
Edition 5.0 2023-03
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –

Part 6-2: Application layer protocol specification – Type 2 elements

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 25.040.40; 35.100.70; 35.110 ISBN 978-2-8322-6631-1

– 2 – IEC 61158-6-2:2023 © IEC 2023
CONTENTS
FOREWORD . 14
INTRODUCTION . 17
1 Scope . 18
1.1 General . 18
1.2 Specifications . 18
1.3 Conformance . 19
2 Normative references . 19
3 Terms, definitions, symbols, abbreviated terms and conventions . 21
3.1 Terms and definitions from other ISO/IEC standards . 21
3.1.1 Terms and definitions from ISO/IEC 7498-1 . 21
3.1.2 Terms and definitions from ISO/IEC 9545 . 21
3.1.3 Terms and definitions from ISO/IEC 8824-1 . 22
3.1.4 Terms and definitions from ISO/IEC 8825-1 . 22
3.2 Terms and definitions from IEC 61158-5-2 . 22
3.3 Additional terms and definitions . 22
3.4 Abbreviated terms and symbols . 30
3.5 Conventions . 30
3.5.1 General concept . 30
3.5.2 Attribute specification . 31
3.5.3 Common services . 31
3.5.4 State machine conventions . 34
4 Abstract syntax . 36
4.1 FAL PDU abstract syntax . 36
4.1.1 General . 36
4.1.2 PDU structure . 36
4.1.3 UCMM_PDUs . 39
4.1.4 Transport_Headers . 40
4.1.5 CM_PDUs . 43
4.1.6 CM PDU components . 56
4.1.7 MR headers . 65
4.1.8 OM_Service_PDU . 66
4.1.9 Message and connection paths . 130
4.1.10 Class, attribute and service codes . 146
4.1.11 Error codes . 154
4.2 Data abstract syntax specification . 169
4.2.1 Transport format specification . 169
4.2.2 Abstract syntax notation . 170
4.2.3 Control network data specification . 170
4.2.4 Data type specification / dictionaries . 172
4.3 Encapsulation abstract syntax . 174
4.3.1 Encapsulation protocol . 174
4.3.2 Encapsulation messages . 175
4.3.3 Command descriptions . 178
4.3.4 Common packet format . 190
5 Transfer syntax . 194
5.1 Compact encoding . 194

5.1.1 Encoding rules . 194
5.1.2 Encoding constraints . 195
5.1.3 Examples. 195
5.2 Data type reporting . 202
5.2.1 Object data representation. 202
5.2.2 Elementary data type reporting . 202
5.2.3 Constructed data type reporting . 203
6 Structure of FAL protocol state machines . 209
7 AP-Context state machine . 210
7.1 Overview. 210
7.2 Connection object state machine . 210
7.2.1 I/O Connection instance behavior . 210
7.2.2 Bridged Connection instance behavior . 215
7.2.3 Explicit Messaging Connection instance behavior . 217
8 FAL service protocol machine (FSPM) . 219
8.1 General . 219
8.2 Primitive definitions . 219
8.3 Parameters of primitives . 224
8.4 FSPM state machines . 225
9 Application relationship protocol machines (ARPMs) . 225
9.1 General . 225
9.2 Connection-less ARPM (UCMM) . 226
9.2.1 General . 226
9.2.2 Primitive definitions . 226
9.2.3 Parameters of primitives . 227
9.2.4 UCMM state machines . 228
9.2.5 Examples of UCMM sequences . 233
9.2.6 Management UCMM . 235
9.3 Connection-oriented ARPMs (transports) . 236
9.3.1 Transport PDU buffer . 236
9.3.2 Transport classes . 237
9.3.3 Common primitive definitions . 237
9.3.4 Parameters of common primitives . 238
9.3.5 Transport state machines – class 0 . 238
9.3.6 Transport state machines – class 1 . 242
9.3.7 Transport state machines – class 2 . 247
9.3.8 Transport state machines – class 3 . 255
10 DLL mapping protocol machine 1 (DMPM 1) . 265
10.1 General . 265
10.2 Link producer . 265
10.3 Link consumer . 266
10.4 Primitive definitions . 266
10.4.1 Primitives exchanged between DMPM and ARPM . 266
10.4.2 Parameters of ARPM/DMPM primitives . 266
10.4.3 Primitives exchanged between data-link layer and DMPM . 266
10.4.4 Parameters of DMPM/Data-link Layer primitives . 267
10.4.5 Network connection ID . 268
10.5 DMPM state machine . 268

– 4 – IEC 61158-6-2:2023 © IEC 2023
10.5.1 DMPM states . 268
10.5.2 Functions used by DMPM . 270
10.6 Data-link Layer service selection. 270
11 DLL mapping protocol machine 2 (DMPM 2) . 270
11.1 General . 270
11.2 Mapping of UCMM PDUs . 270
11.2.1 General . 270
11.2.2 Common requirements for Connection Manager PDU's . 272
11.2.3 Forward_Open PDU for class 2 and class 3 connections . 274
11.2.4 Forward_Open for class 0 and class 1 connections. 274
11.2.5 Forward_close . 279
11.3 Mapping of transport class 0 and class 1 PDUs. 279
11.3.1 Class 0 and class 1 PDUs. 279
11.3.2 No dependency on TCP connections . 279
11.3.3 Class 0 and class 1 packet ordering . 280
11.3.4 Screening incoming connected data . 280
11.4 Mapping of transport class 2 and class 3 PDU's . 280
11.5 IGMP Usage . 281
11.5.1 Background (informative) . 281
11.5.2 IGMP Membership Report messages . 282
11.5.3 IGMP Leave Group messages . 282
11.6 Quality of Service (QoS) for Type 2 Ethernet messages . 282
11.6.1 Overview . 282
11.6.2 DSCP format . 283
11.6.3 IEEE Std 802.1Q-2018 format . 284
11.6.4 Mapping Type 2 traffic to DSCP and IEEE Std 802.1Q-2018 . 284
11.6.5 Usage of DSCP for Type 2 Ethernet . 285
11.6.6 Usage of IEEE Std 802.1Q-2018 for Type 2 Ethernet . 285
11.6.7 User considerations with IEEE Std 802.1Q-2018 . 286
11.7 Encapsulation using TCP . 286
11.7.1 General . 286
11.7.2 Management of a TCP encapsulation session . 286
11.7.3 TCP connection management . 287
11.8 Encapsulation using UDP . 288
12 DLL mapping protocol machine 3 (DMPM 3) . 288
Bibliography . 289

Figure 1 – Attribute table format and terms . 31
Figure 2 – Service request/response parameter . 31
Figure 3 – Example of an STD . 34
Figure 4 – Network connection parameters . 56
Figure 5 – Priority/Tick_time bit definition . 59
Figure 6 – Member ID/EX description (WORD). 74
Figure 7 – Transport Class Trigger attribute . 118
Figure 8 – DN_initial_comm_characteristics attribute format . 122
Figure 9 – Segment type . 131
Figure 10 – Port segment . 132

Figure 11 – Logical segment encoding . 134
Figure 12 – Extended network segment . 141
Figure 13 – Symbolic segment encoding . 142
Figure 14 – Encapsulation message . 175
Figure 15 – FixedLengthBitString compact encoding bit placement rules . 199
Figure 16 – Example compact encoding of a SWORD FixedLengthBitString . 199
Figure 17 – Example compact encoding of a WORD FixedLengthBitString . 199
Figure 18 – Example compact encoding of a DWORD FixedLengthBitString . 200
Figure 19 – Example compact encoding of a LWORD FixedLengthBitString . 200
Figure 20 – Example 1 of formal encoding of a structure type specification . 205
Figure 21 – Example 2 of formal encoding of a structure type specification . 205
Figure 22 – Example 3 of formal encoding of a handle structure type specification . 206
Figure 23 – Example 4 of formal encoding of a handle structure type specification . 206
Figure 24 – Example 5 of abbreviated encoding of a structure type specification . 207
Figure 25 – Example 1 of formal encoding of an array type specification. 207
Figure 26 – Example 2 of formal encoding of an array type specification. 208
Figure 27 – Example 1 of abbreviated encoding of an array type specification . 209
Figure 28 – Example 2 of abbreviated encoding of an array type specification . 209
Figure 29 – I/O Connection object state transition diagram . 210
Figure 30 – Bridged Connection object state transition diagram . 215
Figure 31 – Explicit Messaging Connection object state transition diagram . 217
Figure 32 – State transition diagram of UCMM client9 . 229
Figure 33 – State transition diagram of high–end UCMM server . 231
Figure 34 – State transition diagram of low–end UCMM server . 233
Figure 35 – Sequence diagram for a UCMM with one outstanding message . 234
Figure 36 – Sequence diagram for a UCMM with multiple outstanding messages . 235
Figure 37 – TPDU buffer . 236
Figure 38 – Data flow diagram using a client transport class 0 and server transport
class 0 . 239
Figure 39 – Sequence diagram of data transfer using transport class 0 . 239
Figure 40 – Class 0 client STD . 240
Figure 41 – Class 0 server STD . 241
Figure 42 – Data flow diagram using client transport class 1 and server transport

class 1 . 242
Figure 43 – Sequence diagram of data transfer using client transport class 1 and
server transport class 1 . 243
Figure 44 – Class 1 client STD . 245
Figure 45 – Class 1 server STD . 246
Figure 46 – Data flow diagram using client transport class 2 and server transport
class 2 . 248
Figure 47 – Diagram of data transfer using client transport class 2 and server transport

class 2 without returned data . 249
Figure 48 – Sequence diagram of data transfer using client transport class 2 and
server transport class 2 with returned data . 250
Figure 49 – Class 2 client STD . 251

– 6 – IEC 61158-6-2:2023 © IEC 2023
Figure 50 – Class 2 server STD . 253
Figure 51 – Data flow diagram using client transport class 3 and server transport
class 3 . 256
Figure 52 – Sequence diagram of data transfer using client transport class 3 and
server transport class 3 without returned data . 257
Figure 53 – Sequence diagram of data transfer using client transport class 3 and
server transport class 3 with returned data . 258
Figure 54 – Class 3 client STD . 260
Figure 55 – Class 3 server STD . 263
Figure 56 – Data flow diagram for a link producer and consumer . 265
Figure 57 – State transition diagram for a link producer . 269
Figure 58 – State transition diagram for a link consumer . 270
Figure 59 – DS field in the IP header . 284
Figure 60 – IEEE Std 802.1Q-2018 tagged frame . 284

Table 1 – Get_Attributes_All response service rules . 32
Table 2 – Example class level object/service specific response data of
Get_Attributes_All . 32
Table 3 – Set_Attributes_All request service rules . 33
Table 4 – Example request data of Set_Attributes_All . 33
Table 5 – State event matrix format . 35
Table 6 – Example state event matrix . 35
Table 7 – UCMM_PDU header format . 39
Table 8 – UCMM command codes . 39
Table 9 – Transport class 0 header . 40
Table 10 – Transport class 1 header . 40
Table 11 – Transport class 2 header . 40
Table 12 – Transport class 3 header . 41
Table 13 – Real-time data header – exclusive owner . 41
Table 14 – Real-time data header– redundant owner . 41
Table 15 – Forward_Open request format . 46
Table 16 – Forward_Open_Good response format . 47
Table 17 – Forward_Open_Bad response format . 47
Table 18 – Large_Forward_Open request format . 48
Table 19 – Large_Forward_Open_Good response format . 49
Table 20 – Large_Forward_Open_Bad response format . 49
Table 21 – Forward_Close request format. 50
Table 22 – Forward_Close_Good response format . 50
Table 23 – Forward_Close_Bad response format . 51
Table 24 – Unconnected_Send request format . 52
Table 25 – Unconnected_Send_Good response format . 52
Table 26 – Unconnected_Send_Bad response format . 53
Table 27 – Get_Connection_Data request format . 54
Table 28 – Get_Connection_Data response format . 54

Table 29 – Search_Connection_Data request format . 55
Table 30 – Get_Connection_Owner request format . 55
Table 31 – Get_Connection_Owner response format . 56
Table 32 – Time-out multiplier . 59
Table 33 – Tick time units . 60
Table 34 – Encoded application path ordering. 64
Table 35 – Transport class, trigger and Is_Server format . 65
Table 36 – MR_Request_Header format . 65
Table 37 – MR_Response_Header format . 66
Table 38 – Structure of Get_Attributes_All_ResponsePDU body . 66
Table 39 – Structure of Set_Attributes_All_RequestPDU body . 67
Table 40 – Structure of Get_Attribute_List_RequestPDU body . 67
Table 41 – Structure of Get_Attribute_List_ResponsePDU body . 67
Table 42 – Structure of Set_Attribute_List_RequestPDU body . 67
Table 43 – Structure of Set_Attribute_List_ResponsePDU body . 68
Table 44 – Structure of Reset_RequestPDU body . 68
Table 45 – Structure of Reset_ResponsePDU body . 68
Table 46 – Structure of Start_RequestPDU body . 68
Table 47 – Structure of Start_ResponsePDU body . 68
Table 48 – Structure of Stop_RequestPDU body . 69
Table 49 – Structure of Stop_ResponsePDU body . 69
Table 50 – Structure of Create_RequestPDU body . 69
Table 51 – Structure of Create_ResponsePDU body . 69
Table 52 – Structure of Delete_RequestPDU body . 69
Table 53 – Structure of Delete_ResponsePDU body . 70
Table 54 – Structure of Get_Attribute_Single_ResponsePDU body . 70
Table 55 – Structure of Set_Attribute_Single_RequestPDU body . 70
Table 56 – Structure of Set_Attribute_Single_ResponsePDU body . 70
Table 57 – Structure of Find_Next_Object_Instance_RequestPDU body . 71
Table 58 – Structure of Find_Next_Object_Instance_ResponsePDU body . 71
Table 59 – Structure of Apply_Attributes_RequestPDU body . 71
Table 60 – Structure of Apply_Attributes_ResponsePDU body . 71
Table 61 – Structure of Save_RequestPDU body . 71
Table 62 – Structure of Save_ResponsePDU body . 72
Table 63 – Structure of Restore_RequestPDU body . 72
Table 64 – Structure of Restore_ResponsePDU body . 72
Table 65 – Structure of Get_Member_ResponsePDU body . 72
Table 66 – Structure of Set_Member_RequestPDU body . 72
Table 67 – Structure of Set_Member_ResponsePDU body . 73
Table 68 – Structure of Insert_Member_RequestPDU body . 73
Table 69 – Structure of Insert_Member_ResponsePDU body . 73
Table 70 – Structure of Remove_Member_ResponsePDU body . 73
Table 71 – Common structure of _Member_RequestPDU body (basic format) . 74

– 8 – IEC 61158-6-2:2023 © IEC 2023
Table 72 – Common structure of _Member_ResponsePDU body (basic format) . 75
Table 73 – Common structure of _Member_RequestPDU body (extended format) . 75
Table 74 – Common structure of _Member_ResponsePDU body (extended format) . 75
Table 75 – Extended Protocol ID. 76
Table 76 – Structure of _Member_RequestPDU body (Multiple Sequential Members) . 76
Table 77 – Structure of _Member_ResponsePDU body (Multiple Sequential Members) . 76
Table 78 – Structure of _Member_RequestPDU body (International String Selection) . 77
Table 79 – Structure of _Member_ResponsePDU body (International String Selection) . 77
Table 80 – Structure of Group_Sync_RequestPDU body . 77
Table 81 – Structure of Group_Sync_ResponsePDU body . 78
Table 82 – Structure of Multiple_Service_Packet_RequestPDU body . 78
Table 83 – Structure of Multiple_Service_Packet_ResponsePDU body . 78
Table 84 – Structure of Get_Connection_Point_Member_List_ResponsePDU body . 79
Table 85 – Identity object class attributes . 80
Table 86 – Identity object instance attributes . 80
Table 87 – Identity object Vendor ID ranges . 83
Table 88 – Identity object bit definitions for status instance attribute . 83
Table 89 – Default values for extended device status field (bits 4 to 7) of status
instance attribute . 83
Table 90 – Identity object bit definitions for protection mode instance attribute . 84
Table 91 – Identity object bit definitions for features supported attribute . 84
Table 92 – Class level object/service specific response data of Get_Attributes_All . 84
Table 93 – Instance level object/service specific response data of Get_Attributes_All . 85
Table 94 – Object-specific request parameter for Reset . 86
Table 95 – Reset service parameter values . 86
Table 96 – Communication link attributes that shall be preserved . 86
Table 97 – Structure of Flash_LEDs_RequestPDU body . 87
Table 98 – Message Router object class attributes . 87
Table 99 – Message Router object instance attributes . 87
Table 100 – Class level object/service specific response data of Get_Attributes_All . 88
Table 101 – Instance level object/service specific response data of Get_Attributes_All . 88
Table 102 – Structure of Symbolic_Translation_RequestPDU body . 88
Table 103 – Structure of Symbolic_Translation_ResponsePDU body . 88
Table 104 – Object specific status for Symbolic_Translation service . 89
Table 105 – Structure of Send_Receive_Fragment_RequestPDU body – Phase 1 . 89
Table 106 – Structure of Send_Receive_Fragment_RequestPDU body – Phase 2 . 89
Table 107 – Structure of Send_Receive_Fragment_ResponsePDU body – Phase 2 . 90
Table 108 – Request/Response Fragmentation Flags . 90
Table 109 – Fragmentation Flags Usage . 90
Table 110 – Object specific status for Send_Receive_Fragment service . 91
Table 111 – Assembly object class attributes . 92
Table 112 – Assembly object instance attributes . 92
Table 113 – Assembly Instance ID ranges . 93

Table 114 – Standard Network Diagnostic assembly content and ordering . 94
Table 115 – Object-specific request parameter for Create . 94
Table 116 – Object-specific response parameter for Create . 95
Table 117 – Acknowledge Handler object class attributes . 95
Table 118 – Acknowledge Handler object instance attributes . 95
Table 119 – Structure of Add_AckData_Path_RequestPDU body . 96
Table 120 – Structure of Remove_AckData_Path_RequestPDU body . 96
Table 121 – Time Sync object class attributes . 96
Table 122 – Time Sync object instance attributes . 97
Table 123 – ClockIdentity encoding for different network implementations . 101
Table 124 – ClockClass values . 101
Table 125 – TimeAccuracy values . 102
Table 126 – TimePropertyFlags bit values . 102
Table 127 – TimeSource values . 103
Table 128 – Types of Clock . 103
Table 129 – Network protocol to PortPhysicalAddressInfo mapping . 103
Table 130 – Time Sync connection point 1, Standard Network Diagnostics . 104
Table 131 – Class level object/service specific response data of Get_Attributes_All . 104
Table 132 – Parameter object class attributes . 105
Table 133 – Parameter Class Descriptor bit values . 105
Table 134 – Parameter object instance attributes. 106
Table 135 – Semantics of Descriptor Instance attribute . 107
Table 136 – Descriptor Scaling bits usage . 107
Table 137 – Minimum and Maximum Value semantics . 108
Table 138 – Scaling Formula attributes . 109
Table 139 – Scaling links . 109
Table 140 – Class level object/service specific response data of Get_Attributes_All . 110
Table 141 – Instance level object/service specific response data of Get_Attributes_All
(Parameter object stub) . 110
Table 142 – Instance level object/service specific response data of Get_Attributes_All
(full Parameter object) . 111
Table 143 – Structure of Get_Enum_String_RequestPDU body. 112
Table 144 – Structure of Get_Enum_String_ResponsePDU body . 112
Table 145 – Enumerated strings Type versus Parameter data type . 112
Table 146 – Connection Manager object class attributes . 113
Table 147 – Connection Manager object instance attributes . 113
Table 148 – Connection Manager connection point 1, Standard Network Diagnostics . 114
Table 149 – Class level object/service specific response data of Get_Attributes_All . 114
Table 150 – Instance level object/service specific response data of Get_Attributes_All . 115
Table 151 – Instance level object/service specific request data of Set_Attributes_All . 115
Table 152 – Connection object class attributes . 116
Table 153 – Connection object instance attributes . 116
Table 154 – Values assigned to the state attribute . 117
Table 155 – Values assigned to the instance_type attribute . 118

– 10 – IEC 61158-6-2:2023 © IEC 2023
Table 156 – Possible values within Direction Bit . 119
Table 157 – Possible values within Production Trigger Bits .
...