1.1 General

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 IEC 61158-5-20, and
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) and the OSI Application Layer Structure (ISO/IEC 9545).

1.2 Specifications

The principal objective of this standard is to specify the syntax and behavior of the application layer protocol that conveys the application layer services defined in IEC 61158-5-20.

A secondary objective is to provide migration paths from previously-existing industrial communications protocols. It is this latter objective which gives rise to the diversity of protocols standardized in IEC 61158-6.

PDF Catalog

PDF Pages	PDF Title
6	CONTENTS
9	INTRODUCTION
10	1 Scope 1.1 General 1.2 Specifications
11	1.3 Conformance 2 Normative references
12	3 Terms, definitions, symbols, abbreviations and conventions 3.1 Terms and definitions from other ISO/IEC standards 3.2 IEC/TR 61158-1 terms
15	3.3 Type 20 fieldbus application-layer specific definitions
17	3.4 Abbreviations and symbols
18	3.5 Conventions 3.6 Conventions used in state machines Tables Table 1 – Conventions used for state machines
19	4 Abstract syntax 5 Transfer syntax 5.1 General
20	5.2 Common APDU structure Figures Figure 1 – APDU format Figure 2 – Normal response from slave to master
21	Figure 3 – Command error response from slave to master Table 2 – Response code values Table 3 – Device status values
22	5.3 Service-specific APDU structures Figure 4 – Communication error response from slave to master Table 4 – Response code values Table 5 – Communication error codes
23	Table 6 – Identify request APDU
24	Table 7 – Identify response value field Table 8 – Identify command specific response codes
25	Table 9 – Read primary variable response value field Table 10 – Read primary variable command specific response codes Table 11 – Read loop current and percent of range value field
26	Table 12 – Read loop current and percent of range command specific response codes Table 13 – Read dynamic variables and loop current value field Table 14 – Read dynamic variables and loop current command specific response codes
27	Table 15 – Write polling address value field Table 16 – Loop current mode codes Table 17 – Write polling address command specific response codes
28	Table 18 – Read loop configuration value field Table 19 – Read loop configuration command specific response codes Table 20 – Read dynamic variable families classifications value field
29	Table 21 – Read dynamic variable families classifications command specific response codes Table 22 – Read device variables with status request value field Table 23 – Read device variables with status value field
31	Table 24 – Variable status values Table 25 – Read device variables with status command specific response codes
32	Table 26 – Read message response value field Table 27 – Read message command specific response codes Table 28 – Read tag, descriptor, date response value field Table 29 – Read tag, descriptor, date command specific response codes
33	Table 30 – Read primary variable transducer information response value field Table 31 – Read primary variable transducer information command specific response codes
34	Table 32 – Read device information response value field Table 33 – Read device information command specific response codes Table 34 – Read final assembly number response value field
35	Table 35 – Read final assembly number command specific response codes Table 36 – Write message value field Table 37 – Write message command specific response codes Table 38 – Write tag, descriptor, date value field
36	Table 39 – Write tag, descriptor, date command specific response codes Table 40 – Write final assembly number value field Table 41 – Write final assembly number command specific response codes
37	5.4 Data coding rules Table 42 – Read long tag response value field Table 43 – Read long tag command-specific response codes Table 44 – Write long tag value field Table 45 – Write long tag command specific Response codes
38	Figure 5 – Coding without identification Figure 6 – Coding of Integer type data Figure 7 – Coding of Integer16 type data Figure 8 – Coding of Unsigned type data Figure 9 – Coding of Unsigned16 type data
39	Figure 10 – Coding of single precision Floating Point type data
40	Figure 11 – Coding of double precision Floating Point type data Figure 12 – Coding of Date type data Table 46 – Coding for Date type
41	Table 47 – Coding for one octet Enumerated Type
42	Table 48 – One octet bit field Table 49 – Packed ASCII character set
43	6 Structure of FAL protocol state machines Table 50 – AccepTable subset of ISO Latin-1 characters
44	7 AP-context state machines 8 FAL service protocol machine (FSPM) 8.1 General Figure 13 – Relationships among protocol machines and adjacent layers
45	8.2 FSPM state tables Figure 14 – State transition diagram of FSPM Table 51 – FSPM state Table – client transactions
49	Table 52 – FSPM state Table – server transactions
50	8.3 Functions used by FSPM 8.4 Parameters of FSPM/ARPM primitives Table 53 – Function Command () Table 54 – Function CommErr () Table 55 – Function CommandErr () Table 56 – Function Resp () Table 57 – Function Device () Table 58 – Parameters used with primitives exchanged between FSPM and ARPM
51	9 Application relationship protocol machines (ARPMs) 9.1 AREP mapping to data link layer
52	9.2 Application relationship protocol machines (ARPMs) Figure 15 – State transition diagram of the client ARPM Table 59 – Client ARPM states
53	Figure 16 – State transition diagram of the server ARPM Table 60 – Client ARPM state table Table 61 – Server ARPM states Table 62 – Server ARPM state table
54	9.3 AREP state machine primitive definitions 9.4 AREP state machine functions 10 DLL mapping protocol machine (DMPM) Table 63 – Primitives issued from ARPM to DMPM Table 64 – Primitives issued by DMPM to ARPM Table 65 – Parameters used with primitives exchanged between ARPM and DMPM
55	10.1 DMPM states 10.2 DMPM state machines 10.3 Primitives exchanged between data link layer and DMPM Figure 17 – State transition diagram of DMPM Table 66 – DMPM state descriptions Table 67 – DMPM state Table – Client transactions Table 68 – DMPM state Table – Server transactions
56	10.4 Functions used by DMPM Table 69 – Primitives exchanged between data-link layer and DMPM
57	Bibliography

Published By	Publication Date	Number of Pages
BSI	2012	60


PDF Format	Searchable	Printable	Preview Now

Status	Withdrawn
Title	Industrial communication networks. Fieldbus specifications – Application layer protocol specification. Type 20 elements
Replaces	BS EN 61158-6-20:2008
Publisher	BSI
Committee	GEL/65/3
Pages	60
Publication Date	2012-07-31
Withdrawn Date	2014-11-30
Replaced By	BS EN 61158-6-20:2014
ISBN	978 0 580 71571 6
Standard Number	BS EN 61158-6-20:2012
Identical National Standard Of	EN 61158-6-20:2012, IEC 61158-6-20:2010
Descriptors	Interfaces (data processing), Fieldbus, Open systems interconnection, Computer networks, Data transmission, Industrial, Process control, Application layer (OSI), Bus networks, Communication procedures, Automatic control systems, Communication networks
ICS Codes	25.040.40 - Industrial process measurement and control

BS EN 61158-6-20:2012

PDF Catalog