The Fieldbus Application Layer (FAL) provides user programs with a means to access the fieldbus communication environment. In this respect, the FAL can be viewed as a “window between corresponding application programs.”

This standard provides common elements for basic time-critical and non-time-critical messaging communications between application programs in an automation environment and material specific to Type 20 fieldbus. The term “time-critical” is used to represent the presence of a time-window, within which one or more specified actions are required to be completed with some defined level of certainty. Failure to complete specified actions within the time window risks failure of the applications requesting the actions, with attendant risk to equipment, plant and possibly human life.

This standard defines in an abstract way the externally visible behavior provided by the Type 20 of the fieldbus Application Layer in terms of

the abstract syntax defining the application layer protocol data units conveyed between communicating application entities,
the transfer syntax defining the application layer protocol data units conveyed between communicating application entities,
the application context state machine defining the application service behavior visible between communicating application entities; and
the application relationship state machines defining the communication behavior visible between communicating application entities; and.

The purpose of this standard is to define the protocol provided to define

the wire-representation of the service primitives defined in
the externally visible behavior associated with their transfer.

This standard specifies the protocol of the Type 20 IEC) fieldbus application layer, in conformance with the OSI) Basic Reference Model ( ISO/IEC 7498‑1 ) and the OSI) Application Layer Structure ( ISO/IEC 9545 ).

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PDF Pages	PDF Title
4	Foreword Endorsement notice
5	Annex ZA (normative) Normative references to international publications with their corresponding European publications
6	English CONTENTS
11	INTRODUCTION
12	1 Scope 2 Normative references
13	3 Terms, definitions, symbols, abbreviations and conventions 3.1 Terms and definitions from other ISO/IEC standards
14	3.2 IEC 611581 terms
16	3.3 Type 20 fieldbus application-layer specific definitions
19	3.4 Abbreviations and symbols
20	3.5 Conventions 3.6 Conventions used in state machines
21	Tables Table 1 – Conventions used for state machines
22	4 Abstract syntax 5 Transfer syntax 5.1 Common APDU fields Table 2 – Response code values
23	Table 3 – Application process status values Table 4 – Extended status values
24	5.2 Common APDU structure Figures Figure 1 – Request APDU Figure 2 – Normal response APDU
25	Figure 3 – Command error response from slave to master
26	5.3 Device application service-specific APDU structures Figure 4 – Aggregated command APDU Table 5 – Identify request APDU
27	Table 6 – Identify response value field Table 7 – Identify command specific response codes
28	Table 8 – Read primary variable response value field Table 9 – Read primary variable command specific response codes Table 10 – Read loop current and percent of range value field
29	Table 11 – Read loop current and percent of range command specific response codes Table 12 – Read dynamic variables and loop current value field Table 13 – Read dynamic variables and loop current command specific response codes
30	Table 14 – Write loop configuration value field Table 15 – Write loop configuration command specific response codes
31	Table 16 – Read loop configuration value field Table 17 – Read loop configuration command specific response codes Table 18 – Read dynamic variable families classifications value field Table 19 – Read dynamic variable families classificationscommand specific response codes
32	Table 20 – Read device variables with status request value field Table 21 – Read device variables with status value field
33	Table 22 – Read device variables with status command specific response codes
34	Table 23 – Read message response value field Table 24 – Read message command specific response codes
35	Table 25 – Read tag, descriptor, date response value field Table 26 – Read tag, descriptor, date command specific response codes Table 27 – Read primary variable transducer information response value field
36	Table 28 – Read primary variable transducer informationcommand specific response codes Table 29 – Read device information response value field
37	Table 30 – Read device information command specific response codes Table 31 – Read final assembly number response value field Table 32 – Read final assembly number command specific response codes Table 33 – Write message value field
38	Table 34 – Write message command specific response codes Table 35 – Write tag, descriptor, date value field Table 36 – Write tag, descriptor, date command specific response codes
39	Table 37 – Write final assembly number value field Table 38 – Write final assembly number command specific response codes Table 39 – Read long tag response value field Table 40 – Read long tag command-specific response codes
40	Table 41 – Write long tag value field Table 42 – Write long tag command specific Response codes
41	Table 43 – Write primary variable range value field Table 44 – Write primary variable range command specific response codes
42	Table 45 – Enter-exit fixed current mode request value field Table 46 – Enter-exit fixed current mode response value field Table 47 – Enter-exit fixed current mode command specific response codes
43	Table 48 – Write primary variable unit value field Table 49 – Write primary variable unit command specific response codes Table 50 – Trim loop current zero request value field Table 51 – Trim loop current zero command specific response codes
44	Table 52 – Trim loop current gain request value field Table 53 – Trim loop current gain command specific response codes
45	Table 54 – Read dynamic variable assignment response value field Table 55 – Read dynamic variable assignment command specific response codes
46	Table 56 – Write dynamic variable assignment value field Table 57 – Write dynamic variable assignment command specific response codes
47	Table 58 – Write number of response preambles value field Table 59 – Write number of response preambles command specific response codes Table 60 – Read device variable trim points request value field
48	Table 61 – Read device variable trim points response value field Table 62 – Read device variable trim points command specific response codes Table 63 – Read device variable trim guidelines request value field Table 64 – Read device variable trim guidelines response value field
49	Table 65 – Read device variable trim points command specific response codes Table 66 – Write device variable trim point value field
50	Table 67 – Write device variable trim point command specific response codes Table 68 – Reset device variable trim value field
51	Table 69 – Reset device variable trim command specific response codes
52	Table 70 – Aggregated command specific response codes
53	5.4 Data coding rules Figure 5 – Coding without identification Figure 6 – Coding of Integer type data
54	Figure 7 – Coding of Integer16 type data Figure 8 – Coding of Unsigned type data Figure 9 – Coding of Unsigned16 type data Figure 10 – Coding of single precision Floating Point type data
55	Figure 11 – Coding of double precision Floating Point type data Figure 12 – Coding of Date type data Table 71 – Coding for Date type
56	Table 72 – Coding for one octet Enumerated Type Table 73 – One octet bit field
57	Table 74 – Packed ASCII character set
58	6 Common procedures 6.1 Delayed response 6.2 Publish mode procedure 7 FAL protocol state machines 7.1 General Table 75 – Acceptable subset of ISO Latin-1 characters
59	7.2 AREP mapping to data link layer
60	7.3 Client ARPM Figure 13 – Client state machine
61	Table 76 – Client machine state transitions
62	7.4 Server ARPM Figure 14 – Server state machine
63	7.5 Functions used by FAL state machines Table 77 – Server machine state transitions Table 78 – Function FormReqApdu Table 79 – Function Command Table 80 – Function CommErr
64	Table 81 – Function RespCode Table 82 – Function Commcode Table 83 – Function ApStatus Table 84 – Function Value
65	Annex A (normative) Application process status A.1 General A.2 Device malfunction A.3 Configuration changed Table A.1 – Commands that cause configuration change
66	A.4 Cold start A.5 More status available A.6 Loop current fixed A.7 Loop current saturated
67	A.8 Non-primary variable out of limits A.9 Primary variable out of limits Figure A.1 – Loop current saturation and alarm levels
68	Annex B (normative) Device and dynamic variable B.1 Device variable B.2 Dynamic variable Figure B.1 – Device and Dynamic variables
69	B.3 Primary variable Figure B.2 – Primary variable domains
70	B.4 Device variable classification B.5 Device families B.6 Device variable status
71	Figure B.3 – Device variable status
72	Annex C (normative) Common tables C.1 Overview C.2 Table definitions
73	Table C.1 – Transfer function codes
74	Table C.2 – Alarm Selection codes Table C.3 – Write Protect codes Table C.4 – Physical layer signalling codes
75	Table C.5 – Flag Assignment codes Table C.6 – Loop current mode codes Table C.7 – Trim point codes Table C.8 – Analog channel flag codes
76	Table C.9 – Device variable codes
77	Annex D (normative) Command requirements D.1 General D.2 Stateless request and response D.3 Read command D.4 Write command D.5 Action command
78	D.6 Indexed command D.7 Multi-transaction command
79	Bibliography

Published By	Publication Date	Number of Pages
BSI	2014	82


PDF Format	Searchable	Printable	Preview Now

Status	Definitive
Pages	82
Publication Date	2014-11-30
ISBN	978 0 580 79479 7
Standard Number	BS EN 61158-6-20:2014
Title	Industrial communication networks. Fieldbus specifications – Application layer protocol specification. Type 20 elements
Identical National Standard Of	EN 60603-7-51:2010, EN 61158-6-20:2014, IEC 61158-6-20:2014
Replaces	BS EN 61158-6-20:2012
Descriptors	Data transmission, Computer networks, Process control, Interfaces (data processing), Open systems interconnection, Communication networks, Industrial, Automatic control systems, Communication procedures, Bus networks, Fieldbus, Application layer (OSI)
Publisher	BSI
Committee	GEL/65/3
ICS Codes	35.110 - Networking

BS EN 61158-6-20:2014

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