Prof.Dr.H.Ziegler CEN/TC176-WG4-N107 Rev.4

Proposal for future M-Bus Application Layer

1. Introduction

The M-Bus application layer describes a standard especially for meter readout. It can be used with various physical layers and with link layers and network layers which support the transmission of variable length binary transparent telegrams. The first byte of an application layer telegram is the CI-field which distinguishes between various telegram types and application functions. It is also used to distinguish between true application layer communication and management commands for lower layers. The meaning of the remaining bytes of the telegram depends also on the value of the CI-field. This second revision is a compatible enhancement of the sections 6.4 to 6.6 of the original standard EN1434-part 3 (1997). Besides some clarifications and implementation hints it contains optional enhancements especially for complex meters. Due to technical progress some variants (Fixed format and mode 2=high byte first) are no longer recommended for new developments but are still included as a reference.

Note that this standard contains only directions how data should be coded. It is beyond the task of an application layer standard to define which data must be transmitted under what conditions by which types of slaves or which data transmitted to a slave must have which reactions. Therefore adherence to this standard guarantees the coexistance and common communication and readout capability of slaves via a universal master software (covering all optional features), but not yet functional or communication interchangeabilty of meters following this standard. For several meter types and meter classes the company "Fernwärme Wien" and the "AGFW"-group of remote heating users have provided such application descriptions required for full interchangeability. They are accessible via the www-server of the m-bus users group (http://www.m-bus.com).

2. CI-Field

2.1 OverviewMaster to slave

The original EN1434-3 defined two possible data sequences in multibyte records. The bit two (value 4), which is called M bit or Mode bit, in the CI field gives an information about the used byte sequence in multibyte data structures. If the Mode bit is not set (Mode 1), the least significant byte of a multibyte record is transmitted first, otherwise (Mode 2) the most significant byte. The Mode 2 (M=1) is obsolete and should not be used. It is documented here only as a reference for universal master software with support of old meters.

 

 

Mode 1

(Mode 2)

Application

00h-4Fh

 

reserved for DLMS

50h

 

application reset

51h

(55h)

data send (master to slave)

52h

(56h)

selection of slaves

53h

 

reserved

54h-58h

 

reserved for DLMS

59h-5Bh

 

reserved

5Ch

 

synchronize action

60h-6Fh

 

reserved

70h-7Fh

(74h)

reserved for answer directionslave to master: report of application errors

71h

 

slave to master: report of alarms

72h

(76h)

slave to master: Variable format data respond

73h

(77h)

slave to master: Fixed format data respond

7880h-8Fh

 

reserved

90h-97h

 

manufacturer specific (obsolete)

A0h-AFh

 

manufacturer specific

B0-B7h

 

manufacturer specific (obsolete)

B8h

 

set baudrate to 300 baud

B9h

 

set baudrate to 600 baud

BAh

 

set baudrate to 1200 baud

BBh

 

set baudrate to 2400 baud

BCh

 

set baudrate to 4800 baud

BDh

 

set baudrate to 9600 baud

BEh

 

set baudrate to 19200 baud

BFh

 

set baudrate to 38400 baud

C0h-FFh

 

reserved

Table 1 CI-Field codes used by the master

"Reserved for DLMS" refers to the DLMS PDU´s in A-XDR encoding of the FDIS version of the IEC-DLMS standard. Choosing CI-fields different from these code simplifies the construction of slaves which can have dual application layers for both standards and which then can automatically distinguish between communication according to both standards.

Note that the CI-codes $50, $52/$56, $5C, $70/$74, $71, $A0-$AF and $B8-$BF are optional compatible enhancements of the original standard. Note also that even if the functions of these optional CI-codes are not implemented in a slave the link layer protocol requires a proper link layer acknowledge of SND_UD telegrams containing any of these CI-codes.

2.1.2 Application reset (CI = $50), (optional)

With the CI-Code $50 the master can release a reset of the application layer in the slaves. Each slave himself decides which parameters to change - e.g. which data output is default - after it has received such an application reset. This application reset by a SND_UD with CI=$50 is the counterpart to the reset of the data link layer by a SND_NKE.

2.2.1.3 Application reset subcode (optional)

It is allowed to use optional parameters after CI = $50. If more bytes follow, the first byte is the application reset subcode. Further bytes are ignored. The application reset subcode defines which telegram function and which subtelegram is requested by the master. The datatype of this parameter is 8 bit binary. The upper 4 bits define the telegram type or telegram application and the lower 4 bits define the number of the subtelegram. The lower four bits may me ignored for slaves which provide only a single telegram for each application. The use of the value zero for the number of the subtelegram means that all telegrams are requested.

Slaves with only one type of telegram may ignore application reset and the added parameters but have to confirm it ($E5).

The following codes can be used for the upper 4 bits of the first parameter:

Coding

Description

Examples

0000b

All

 

0001b

User data

consumption

0010b

Simple billing

actual and fixed date values+dates

0011b

Enhanced billing

historic values

0100b

Multi tariff billing

 

0101b

Instaneous values

for regulation

0110b

Load management values for management

 

0111b

Reserved

 

1000b

Installation and startup

bus adress, fixed dates

1001b

Testing

high resolution values

1010b

Calibration

 

1011b

Manufacturing

 

1100b

Development

 

1101b

Selftest

 

1110b

Reserved

 

1111b

Reserved

 

Table 2 Coding of the upper four bits of the first parameter after CI = $50

Note that this table has been expanded with optional elements from the original standard.

 

2.3 Master to slave data send (51h/55h) (optional)

The CI-Field codes 51h(55h) are used to indicate the data send from master to slave:

Variable Data Blocks (Records)

MDH(opt)O

Opt.Mfg.specific data Opt)

variable number

1 Byte

variable number

Fig. 1 Variable Data Structure master to slave

Note that this structure is identical to the slave to master direction (see chapter 4) with the exception of the fixed header which is omitted in this direction.

2.4 Slave select (52h/56h) (optional)

The CI-Field codes 52h(56h) are used for the management of an optional netwerk layer using secondary adressing (See chapter 9).

2.51.4 Synchronize action (CI = $5C) (optional)

This CI-code can be used for synchronizing functions in slaves and masters (e.g. clock synchronization). Special actions or parameter loads may be prepared but their final execution is delayed until the reception of such a special CI-field command.

2.2 Slave to master (answer) codes

The following codes can be used for the direction slave to master:

CI M=0

CI M=1

Application

70h

(74h)

report of general application errors

71h

 

report of alarm status (See Appendix)

72h

(76h)

variable data respond

73h

(77h)

fixed data respond

Table 3 CI-Field codes used by the slave

The use of these control information codes is described in the chapters 3 (fixed data respond), 4 (variable data respond), 6.6 (report of general application errors) and 8.1 (report of alarm status).

2.6 Report of application errors (slave to master) (CI = $70/74) (optional)

3 Fixed Data Structure

For details of the report of application errors see chapter 6.

2.7 Report of alarm status (slave to master) (CI = $71) (optional)

For details of the report of alarm status errors see appendix C.

2.8 Fixed and variable data respond (slave to master) (CI = $72/$76 and $73/$77)

In the reply direction (slave to master) with a long frame originally two different data structures were used. The fixed data structure, besides a fixed length, is limited to the transmission of only two counter states of a predetermined length, which have binary or BCD coding. In contrast the variable data structure allows the transmission of more counter states in various codes and further useful information about the data. The number of bytes of the transmitted counter states is also variable with this data structure. Contrary to the fixed structure, the variable structure can also be used in calling direction. For theseis reasons the fixed data structure is not recommended for future developments. For information on this obsolete fixed data structure see appendix D. For new development therefore only the CI-field $72 shall be used. This is a restriction from the original standard.

To identify the fixed data structure, the numbers 73h/77h for the control information field are used. In this way a universal master software can see how it must interpret the data. For further details on the structure of telegrams starting with CI-values of $72/($76) see chapter 3.

2.9 Baudrate switch commands $B8-$BF (optional)

These optional commands can be used by a master to switch the baudrate of a slave.
For details see chapter 9.1.

3 Data Header of variable data respond 4 Variable Data Structure

4.1 Slave to master (answer) direction

The CI-Field codes 72h/(76h) are used to indicate the variable data structure in long frames (RSP_UD). Figure 2 1 shows the way this data is represented:

Data Header(Req.)

Variable Data Blocks (Records)

MDH(opt)O

Opt.Mfg.specific data Opt)

12 Byte

variable number

1 Byte

variable number

Fig. 12 Variable Data Structure in Answer Direction

3.14.1.1 Structure of Data Header

The first twelve bytes of the user data consist of a block with a fixed length and structure (see fig. 32).

Ident. Nr.

Manufr.

Version

Device typeMedium

Access No.

Status

Signature

4 Byte

2 Byte

1 Byte

1 Byte

1 Byte

1 Byte

2 Byte

Fig. 23 Fixed Data HeaderBlock

3.24.1.2 Identification number

The Identification Number is either a fixed fabrication number or a customer number changable by the customer, coded with 8 BCD packed digits (4 Byte), and which thus runs from 00000000 to 99999999. It can be preset at fabrication time with a unique number, but could be changeable afterwards, especially if in addition an unique and not changeable fabrication number (DIF = $0C, VIF = $78, see chapter 6.7.3) is provided.

34.1.3 Manufacturer identification

The field manufacturer is coded unsigned binary with 2 bytes. This manufacturer ID is calculated from the ASCII code of EN 61107 manufacturer ID (three uppercase letters) with the following formula:

IEC 870 Man. ID = [ASCII(1st letter) - 64] · 32 · 32

+ [ASCII(2nd letter) - 64] · 32

+ [ASCII(3rd letter) - 64]

Note that currently the flag association administers these three letter manufacturers ID of EN61107. For details see appendix X.

34.1.4 Version identification

The field version specifies the generation or version of the meter and depends on the manufacturer. It can be used to make sure, that within each version number the identification # is unique.

34.1.5 Medium Device type identification

The medium device byte is coded as follows:

Device type (previously called medium)Medium

Code bin.

Bit 7 .. 0

Code hex.

Other

0000 0000

00

Oil

0000 0001

01

Electricity

0000 0010

02

Gas

0000 0011

03

Heat (Volume measured at return temperature: outlet)

0000 0100

04

Steam

0000 0101

05

WarmHot Water (30°C-90°C)

0000 0110

06

Water

0000 0111

07

Heat Cost Allocator.

0000 1000

08

Compressed Air

0000 1001

09

Cooling load meter (Volume measured at return temperature: outlet)

0000 1010

0A

Cooling load meter (Volume measured at flow temperature: inlet)

0000 1011

0B

Heat (Volume measured at flow temperature: inlet)

0000 1100

0C

Heat / Cooling load meter

0000 1101

OD

Bus / System component

0000 1110

0E

Unknown Medium

0000 1111

0F

Reserved

..........

10 to 145

Hot water (>=90°C)

0001 0101

15

Cold Water

0001 0110

16

Dual Water

0001 0111

17

Pressure

0001 1000

18

A/D Converter

0001 1001

19

Reserved

..........

20 to FF

Table 3 Device type identification

Note that this table has been expanded with optional elements from the original standard.

3.4.1.6 Access number

The Access Number has unsigned binary coding, and is increased (modulo 256) by one before or after each RSP_UD from the slave. Since it can also be used to enable private end users to detect an unwanted overfrequently readout of its consumption meters, it should not be resettable by any bus communication.

34.1.7 Status byte

Bit

Meaning with Bit set

Significance with Bit not set

0,1

See table 5Fig.4

See table 5Fig.4

2

Power low

Not power low

3

Permanent error

No permanent error

4

Temporary error

No temporary error

5

Specific to manufacturer

Specific to manufacturer

6

Specific to manufacturer

Specific to manufacturer

7

Specific to manufacturer

Specific to manufacturer

Table 4 Fig. 3 Coding of the Status Field

Status bit 1 bit 0

Application status

0 0

No Error

0 1

Application Busy

1 0

Any Application Error

1 1

Reserved

Table 5 Fig. 4 Application Errors coded with the Status-Field

Note that more detailed error signalling can be provided by application telegrams starting with CI=$70 and/or using data records signalling even more detailed error information.

3.8 Signature field

The Signature is reserved for optional encryptation of the application data. If no encryptation is used its value shall be 00 00 h.

3.8.1 Functions

Data privacy for consumption meters values

Detecting simulated meter transmission

Preventing later playback of old meter values

3.8.2 Structure of encrypted telegrams

a) The first 12-byte block containing the ID-number,

the manufacturer etc. is always unencrypted.

The last word of this block is the signature word.

If the following data are unencrypted, this

signature word contains a zero.

b) If the transmission contains encrypted data,

the high byte of this signature word contains a code for

the encryptation method. The code 0 signals no

encryptation. Currently only the encryptation codes 2 or 3

(see below) are defined. The other codes are

reserved. The number of encrypted bytes is contained

in the low byte of the signature word.

The content of this signature word is currently defined

as zero, corresponding consistently to no encrypted data.

c) The encrypted data follow directly after the

signature word, thus forming the beginning of the

DIF/VIF-structured part of the telegram.

 

3.8.3 Partial Encryption

a) If the number of encrypted bytes is less than the

remaining data of the telegram, unencrypted data may

follow after the encrypted data. They must start at a

record boundary, i.e. the first byte after the encrypted

data will be interpreted as a DIF.

b) If a partially encrypted telegram must contain encrypted

manufacturer specific data a record with a suitable length

DIF (possibly a variable length string DIF) and a VIF=

$7F (manufacturer specific data record) must be used

instead of the usual MDH-DIF=$0F. This is required to

enable after decryptation standard DIF/VIF-decoding of a previously partially encrypted telegram containing

encrypted manufacturer specific data .

3.8.4 Encryptation methods

a) Encryptation according to the DES (data encryptation

standard) as described in ANSI X3.92-1981

b) Cipher Block Chaining (CBC)-method as described in

ANSI X3.106-1983 with an initial initialization vector

of zero: (Encryptation Method Code=2). In this case

the data records should contain the current date

before the meter reading.

Note that in this case the data after the date record,

i.e.especially the encrypted meter reading data

change once per day even if their data content itself is

constant. This prevents an undetectable later playback of

stored encrypted meter readings by a hacker.

c) The "Initialization Vector IV" with length 64 bits of this

standard may alternatively be defined by the the first 6

bytes of the identification header in mode 1 sequence,

i.e. identification number in in the lowest 4 bytes

followed by the manufacturer ID in the two next higher

bytes and finally by the current date coded as in record

structure "G" for the two highest bytes.

In this case the encryptation method is coded as "3".

Note that in this case all encrypted data change once

per day even if the data content itself is constant.

This prevents an undetectable later playback of any

stored encrypted data by a hacker.

 

d) To simplify the verification of correct decoding and to

prevent an undetected change in the identification of the

not encrypted header, the encrypted part of the telegram

must contain at least together with the appropriate application

layer coding (DIF and VIF) again the same identification

number as in the unencrypted header.

e) Due to the mathematical nature of the DES-algorithm

the encrypted length contained in the low byte of the

signature word must be an integer multiple of 8 if

the high byte signals DES-encryptation.

Unused bytes in the last 8-byte block must be filled

with appropriatly structured dummy data records to

achieve the required record boundary at the end of the

encrypted data. One or several bytes containing the filler

DIF=$2F are suggested to fill such gaps.

f) The application of certain encryptation methods might be

prohibited by local laws.

 

4.1.8 Signature field

The Signature remains reserved for future encryptation applications, and until then is allocated the value 00 00 h.

Variable Data Blocks (Records)

MDH(opt)O

Opt.Mfg.specific data Opt)

variable number

1 Byte

variable number

Fig. 5 Variable Data Structure in Answer Direction

Note that this structure is identical to the slave to master direction with the exception of the fixed header which is omitted in this direction.

4.3 Variable Data Blocks (Records)

The data, together with information regarding coding, length and the type of data is transmitted in data records in arbitrary sequence. As many records can be transferred as there is room for within the maximum total data length of 234255 Bytes, and taking account of the C, A, and CI fields, and the data header. This limits the total telegram length to 255 bytes. This restriction is required to enable gateways to other link- and application layers. e upper limit for characters in the variable data blocks is thus 240 byte. A maximum total telegram length of 255 bytes (234 bytes for variable data blocks) is recommended to simplify gateways and the integration in other link layers . The manufacturer data header (MDH) is made up by the character 0Fh or 1Fh and indicates the beginning of the manufacturer specific part of the user data and should be omitted, if there are no manufacturer specific data.

DIF

DIFE

VIF

VIFE

Data

1 Byte

0-10 (1 Byte each)

1 Byte

0-10 (1 Byte each)

0-N Byte

Data Information Block DIB

Value Information Block VIB

 

Data Record Header DRH

 

Fig. 46 Structure of a Data Record (transmitted from left to right)

Each data record contains one value (data) with its description (DRH)as shown in figure 20, a data record, which consists of a data record header (DRH) and the actual data. The DRH in turn consists of the DIB (data information block) to describe the length, type and coding of the data, and the VIB (value information block) to give the value of the unit and the multiplier.

4.3.1 Data Information Block (DIB)

The DIB contains at least one byte (DIF, data information field), and can be extended by a maximum of ten DIFE's (data information field extensions).

4.3.2 Data Information Field (DIF)

The following information is contained in a DIF:

Bit 7

6

5

4

3

2

1

0

Extension

Bit

LSB of storage number

Function Field

Data Field :

Length and coding of data

Fig. 57 Coding of the Data Information Field (DIF)

4.3.3 Data Field

The data field shows how the data from the master must be interpreted in respect of length and coding. The following table contains the possible coding of the data field:

Length in Bit

Code

Meaning

Code

Meaning

0

0000

No data

1000

Selection for Readout

8

0001

8 Bit Integer

1001

2 digit BCD

16

0010

16 Bit Integer

1010

4 digit BCD

24

0011

24 Bit Integer

1011

6 digit BCD

32

0100

32 Bit Integer

1100

8 digit BCD

32 / N

0101

32 Bit Real

1101

variable length

48

0110

48 Bit Integer

1110

12 digit BCD

64

0111

64 Bit Integer

1111

Special Functions

Table 46 Coding of the data field

Note that this table has been expanded with optional elements from the original standard.

For a detailed description of data types refer to appendix A8.2 " Coding of data records"
(e.g. BCD = Type A, Integer = Type B, Real = Type H).

 

Variable Length:

With data field = `1101b` several data types with variable length can be used. The length of the data is given after the DRH with the first byte of real data, which is here called LVAR (e.g. LVAR = 02h: ASCII string with two characters follows).

LVAR = 00h .. BFh : Text string according to ISI/IEC 646 with LVAR characters

LVAR = C0h .. C9h : positive BCD number with (LVAR - C0h) · 2 digits

LVAR = D0h .. D9H : negative BCD number with (LVAR - D0h) · 2 digits

LVAR = F8h : floating point number according to IEEE 754

Others LVAR values : Reserved

Like all multibyte fields in mode 1 the last character and in mode 2 the first character is transmitted first.

Special Functions (data field = 1111b):

DIF

Function

0Fh

Start of manufacturer specific data structures to end of user data

1Fh

Same meaning as DIF = 0Fh + More records follow in next telegram

2Fh

Idle Filler (not to be interpreted), following byte = DIF of next record

3Fh..6Fh

Reserved

7Fh

Global readout request (all storage#, units, tariffs, function fields)

Table 7: DIF-coding for special functions

Note that this table has been expanded with optional elements from the original standard.

If data follows after DIF=$0F or $1F these are manufacturer specific unstructured data. The number of bytes in these manufacturer specific data can be calculated from the link layer information on the total length of the application layer telegram. The DIF 1Fh signals a request from the slave to the master to readout the slave once again. The master must readout the slave until there is no DIF=1Fh inside the respond telegram (multi telegram readout) or use an application reset.

 

4.3.4 Function field

The function field gives the type of data as follows:

Code

Description

Code

Description

00b

Instantaneous value

01b

Maximum value

10b

Minimum value

11b

Value during error state

Table 8: Function Field

4.3.5 Storage number

The Bit 6 of the DIF serves as the LSB of the storage number of the data concerned, and the slave can in this way indicate and transmit various stored metering values or historical values of metering data. This bit is the least significant bit of the storage number and allows therefore the storage numbers 0 and 1 to be coded. If storage numbers higher than "1" are needed, following (optional) DIFE´s contain the higher bits. The storage number 0 signals an actual value. Note that a each storage number is associated with a given timepoint. So all data records with the same storage number refer to the value of the associated variable at this (common) timepoint for this storage number. It is recommended, that a time/date record with this storage number is included somewhere to signal this timepoint. Normally (but not necessarily) higher storage numbers indicate an older timepoint. A sequential block of storage numbers can be associated with a sequence of equidistantly spaced time points (profile). Such a block can be described by its starting time, by the time spacing, by the first storage number of such a block and by the length of such a block. The coding for such a block description in contrast to an individual time/date record for each individula storage number is given in the appendix.

4.3.6 Extension Bit

The extension bit (MSB) signals that more detailed or extended descriptions (data field extension=DIFE)-bytes follow.

4.3.7 Data field extension byte(s) (DIFE)

Each DIFE (maximum ten) contains again an extension bit to show whether a further DIFE is being sent. Besides giving the next most significant bits of the storage number, DIFE´s allow the transmission of informations about the tariff and the subunit of the device from which the data come. In this way, exactly as with the storage number, the next most significant bit or bits will be transmitted. The figure 8 which follows shows the structure of a DIFE:

Bit 7

6

5

4

3

2

1

0

Extension Bit

(Device) Unit

Tariff

Storage Number

Fig. 58 Coding of the Data Information Field Extension (DIFE)

With the maximum of ten DIFE´s which are provided, there are 41 bits for the storage number, 20 bits for the tariff, and 10 bits for the subunit of the meter. There is no application conceivable in which this immense number of bits could all be used.

4.3.8 Tariff information

For each (unique) value type designation given by the following value information block (VIB) at each unique time point (given by the storage number) of each unique function (given by the function field) there might exist still various different data, measured or accumulated under different conditions. Such conditions could be time of day, various value ranges of the variable (i.e. separate storage of positive accumulatad values and negative accumulated values) itself or of other signals or variables or various averaging durations. Such variables which could not be distinguished otherwise are made different by assigning them different values of the tariff variable in their data information block. Note that this includes but is not necessarily restricted to various tariffs in a monetary sense. It is at the distinction of the manufacturer to describe for each tariff (except 0) what is different for each tariff number. Again as with the storage numbers all variables with the same tariff information share the same tariff associating condition.

4.93.8 Subunit information

A slave component may consist of several functionally and logically independent subunits of the same or of different functionallity. Such a device may either use several different primary and/or secondary adresses. Such it is from a link layer and an application layer view just several independent devices which share a common physical layer interface. This is recommended for devices which represent a physical collection of several truely independent (often similar or idential) devices. For devices which share common information and values and have logical connections an approach with a common link layer (i.e.a single address) is reccomended. The various subunits can include their specific information into a common telegram and have them differentiated by the individual subunit number in the subunit-datafield of their records.

54.4 Value Information Block (VIB)

After a DIF (with the the exception of $xF) or a DIFE without a set extension bit there follows the VIB (value information block). This consists at least of the VIF (value information field) and can be expanded with a maximum of 10 extensions (VIFE). The VIF and also the VIFE's show with a set MSB that a VIFE will follow. In the value information field VIF the other seven bits give the unit and the multiplier of the transmitted value.

Bit 7

6

5

4

3

2

1

0

Extension Bit

Unit and multiplier (value)

Fig. 69 Coding of the Value Information Field (VIF)

There are five types of coding depending on the VIF:

a)1. Primary VIF: E000 0000b .. E111 1011b

The unit and multiplier is taken from the table for primary VIF (Table 9chapter 8.4.3).

b)2. Plain-text VIF: E111 1100b

In case of VIF = 7Ch / FCh the true VIF is represented by the following ASCII string with the length given in the first byte. Please note that the byte order of the characters after the length byte depends on the used byte sequence. Since only the "LSB first mode" (M=1) of multibyte data transmission is recommended, the rightmost character is transmitted first. This plain text VIF allows the user to code units that are not included in the VIF tables..

c)3. Linear VIF-Extension: FDh and FBh

In case of VIF = FDh and VIF = FBh the true VIF is given by the next byte (i.e. the first VIFE) and the coding is taken from the tables 11 respectively table 12 for secondary VIF (chapter 8.4.4). This extends the available VIF´s by another 256256 codes.

d)4. Any VIF: 7Eh / FEh

This VIF-Code can be used in direction master to slave for readout selection of all VIF´s. See chapter 6.4.3.

e)5. Manufacturer specific: 7Fh / FFh

In this case the remainder of this data record including VIFE´s has manufacturer specific coding.

 

5.1 Primary VIF´s (main table)

The first section of the main table contains integral values, the second typically averaged values, the third typically instantaneous values and the fourth block contains parameters (E: extension bit).

4.4.1 Primary VIF´s (main table)

Coding

Description

Range Coding

Range

E000 0nnn

Energy

10(nnn-3) Wh

0.001Wh to 10000Wh

E000 1nnn

Energy

10(nnn) J

0.001kJ to 10000kJ

E001 0nnn

Volume

10(nnn-6) m3

0.001l to 10000l

E001 1nnn

Mass

10(nnn-3) kg

0.001kg to 10000kg

E010 00nn

On Time

nn = 00 seconds

nn = 01 minutes

nn = 10 hours

nn = 11 days

E010 01nn

Operating Time

coded like OnTime

E010 1nnn

Power

10(nnn-3) W

0.001W to 10000W

E011 0nnn

Power

10(nnn) J/h

0.001kJ/h to 10000kJ/h

E011 1nnn

Volume Flow

10(nnn-6) m3/h

0.001l/h to 10000l/h

E100 0nnn

Volume Flow ext.

10(nnn-7) m3/min

0.0001l/min to 1000l/min

E100 1nnn

Volume Flow ext.

10(nnn-9) m3/s

0.001ml/s to 10000ml/s

E101 0nnn

Mass flow

10(nnn-3) kg/h

0.001kg/h to 10000kg/h

E101 10nn

Flow Temperature

10(nn-3) °C

0.001°C to 1°C

E101 11nn

Return Temperature

10(nn-3) °C

0.001°C to 1°C

E110 00nn

Temperature Difference

10(nn-3) K

1mK to 1000mK

E110 01nn

External Temperature

10(nn-3) °C

0.001°C to 1°C

E110 10nn

Pressure

10(nn-3) bar

1mbar to 1000mbar

E110 110n

Time Point

n = 0 date

n = 1 time & date

data type G

data type F

data type F

E110 1110

Units for H.C.A.

dimensionless

E110 1111

Reserved

E111 00nn

Averaging Duration

coded like OnTime

E111 01nn

Actuality Duration

coded like OnTime

E111 1000

Fabrication No

E111 1001

(Enhanced) Identification

see appendix E2chapter 6.4.2 §

E111 1010

Bus Address

data type C (x=8)

Table 9: Primary VIF-codes

Note that this table has been expanded with optional elements from the original standard.

54.4.2 VIF-Codes for special purposes:

Coding

Description

Purpose

1111 1011

Extension of VIF-codes

true VIF is given in the first VIFE and is coded using

table 108.4.4 b) (128 new VIF-Codes)

E111 1100

VIF in following string

(length in first byte)

allows user definable VIF´s (in plain ASCII-String) *

1111 1101

Extension of VIF-codes

true VIF is given in the first VIFE and is coded using

table 118.4.4 a) (128 new VIF-Codes)

E111 1110

Any VIF

used for readout selection of all VIF´s

(see chapter 9.26.4.3 )

E111 1111

Manufacturer Specific

VIFE´s and data of this block are manufacturer specific

Table 10: Special VIF-Codes

Note that this table has been expanded with optional elements from the original standard.

Note:

* Coding the VIF in an ASCII-String in combination with the data in an ASCII-String (datafield in DIF = 1101 b) allows the representation of data in a free user defined form.

54.4.3 MainFirst VIFE-Code Extension table (following VIF=$FD for primary VIF)

Coding

Description

Group

E000 00nn

Credit of 10nn-3 of the nominal local legal currency units

Currency Units

E000 01nn

Debit of 10nn-3 of the nominal local legal currency units

 

E000 1000

Access Number (transmission count)

 

E000 1001

Device typeMedium (as in fixed header)

 

E000 1010

Manufacturer (as in fixed header)

 

E000 1011

Parameter set identification

Enhanced Identification

E000 1100

Model / Version

 

E000 1101

Hardware version #

 

E000 1110

Firmware version #

 

E000 1111

Software version #

 

E001 0000

Customer location

 

E001 0001

Customer

 

E001 0010

Access Code User

 

E001 0011

Access Code Operator

Implementation of all

E001 0100

Access Code System Operator

TC294 WG1 requirements

E001 0101

Access Code Developer

(improved selection ..)

E001 0110

Password

 

E001 0111

Error flags (binary) (Device type specific)

 

E001 1000

Error mask

 

E001 1001

Reserved

 

E001 1010

Digital Output (binary)

 

E001 1011

Digital Input (binary)

 

E001 1100

Baudrate [Baud]

 

E001 1101

response delay time [bittimes]

 

E001 1110

Retry

 

E001 1111

Reserved

 

E010 0000

First storage # for cyclic storage

 

E010 0001

Last storage # for cyclic storage

 

E010 0010

Size of storage block

 

E010 0011

Reserved

 

E010 01nn

Storage interval [sec(s)..day(s)] Œ

Enhanced storage

E010 1000

Storage interval month(s)

management

E010 1001

Storage interval year(s)

 

E010 1010

Reserved

 

E010 1011

Reserved

 

E010 11nn

Duration since last readout [sec(s)..day(s)] Œ

 

E011 0000

Start (date/time) of tariff 

 

E011 00nn

Duration of tariff (nn=01 ..11: min to days)

 

E011 01nn

Period of tariff [sec(s) to day(s)] Œ

 

E011 1000

Period of tariff months(s)

Enhanced tariff

E011 1001

Period of tariff year(s)

management

E011 1010

dimensionless / no VIF

 

E011 1011

Reserved

 

E011 11xx

Reserved

 

E100 nnnn

10nnnn-9 Volts

electrical units

E101 nnnn

10nnnn-12 A

 

 

 

 

E110 0000

Reset counter

 

E110 0001

Cumulation counter

 

E110 0010

Control signal

 

E110 0011

Day of week

 

E110 0100

Week number

 

E110 0101

Time point of day change

 

E110 0110

State of parameter activation

 

E110 0111

Special supplier information

 

E110 10pp

Duration since last cumulation [hour(s)..years(s)]Ž

 

E110 11pp

Operating time battery

[hour(s)..years(s)]Ž

 

E111 0000

Date and time of battery change

 

E111 0001

to

E111 1111

Reserved

 

Table 11: Main VIFE-code extension table

Note that this optional table has been added to the original standard.

Notes:

Œ nn = 00 second(s)

01 minute(s)

10 hour(s)

11 day(s)

 The information about usage of data type F (date and time) or data type G (date) can be derived from the datafield (0010b: type G / 0100: type F).

Ž pp = 00 hour(s)

01 day(s)

10 month(s)

11 year(s)

 

54.4.4 Alternate VIFE-Code Extension table (following VIF=$FB for primary VIF)

Coding

Description

Range Coding

Range

E000 000n

Energy

10(n-1) MWh

0.1MWh to 1MWh

E000 001n

Reserved

   

E000 01nn

Reserved

   

E000 100n

Energy

10(n-1) GJ

0.1GJ to 1GJ

E000 101n

Reserved

   

E000 11nn

Reserved

   

E001 000n

Volume

10(n+2)

 

E001 001n

Reserved

   

E001 01nn

Reserved

   

E001 100n

Mass

10(n+2) t

100t to 1000t

E001 1010-E010 0000

Reserved

   

E010 0001

Volume

0,1 feet^3

 

E010 0010

Volume

0,1 am.gallon

 

E010 0011

Volume

1 am.gallon

 

E010 0100

Volume flow

0,001 am.gallon/min

 

E010 0101

Volume flow

1 am.gallon/min

 

E010 0110

Volume flow

1 am.gallon/h

 

E010 0111

Reserved

   

E010 100n

Power

10(n-1) MW

0.1MW to 1MW

E010 101n

Reserved

   

E010 11nn

Reserved

   

E011 000n

Power

10(n-1) GJ/h

0.1GJ/hto 1GJ/h

E011 0010-E101 0111

Reserved

   

E101 10nn

Flow Temperature

10(nn-3) °F

0.001°F to 1°F

E101 11nn

Return Temperature

10(nn-3) °F

0.001°F to 1°F

E110 00nn

Temperature Differ.

10(nn-3) °F

0.001°F to 1°F

E110 01nn

Flow Temperature

10(nn-3) °F

0.001°F to 1°F

E110 1nnn

Reserved

   

E111 00nn

Cold/Warm Temp. Lim.

10(nn-3) °F

0.001°F to 1°F

E111 01nn

Cold/Warm Temp. Lim.

10(nn-3) °C

0.001°C to 1°C

E111 1nnn

Cum.Count Max.power

10(nnn-3) W

0.001W to 10000W

Table 12: Alternate extended VIF-code Table

Note that this optional table has been added to the original standard.

54.4.5 Combinable (Orthogonal) VIFE-Code Extension table (Following primary VIF)

VIFE-Code

Description

E00x xxxx

Reserved for object actions (master to slave): see chapter 6.3 and table 16table on page 75

or for error codes (slave to master): see chapter 7 and table 17table on page 74

E010 0000

per second

E010 0001

per minute

E010 0010

per hour

E010 0011

per day

E010 0100

per week

E010 0101

per month

E010 0110

per year

E010 0111

per revolution / measurement

E010 100p

increment per input pulse on input channel #p

E010 101p

increment per output pulse on output channel #p

E010 1100

per liter

E010 1101

per m3

E010 1110

per kg

E010 1111

per K (Kelvin)

E011 0000

per kWh

E011 0001

per GJ

E011 0010

per kW

E011 0011

per (K*l) (Kelvin*liter)

E011 0100

per V (Volt)

E011 0101

per A (Ampere)

E011 0110

multiplied by sek

E011 0111

multiplied by sek / V

E011 1000

multiplied by sek / A

E011 1001

start date(/time) of Œ 

E011 1010

VIF contains uncorrected unit instead of corrected unit

E011 1011

Accumulation only if positive contributions

E011 1100

Accumulation of abs value only if negative contributions

E011 1101 to

E011 1111

Reserved

VIFE-Code

Description

E100 u000

u=1: upper, u=0: lower limit value

E100 u001

# of exceeds of lower u=0) / upper (U=1) limit

E100 uf1b

Date (/time) of: b=0: begin, b=1: end of, f=0: first, f=1: last,

 u=0: lower, u=1: upper limit exceed

E101 ufnn

Duration of limit exceed (u,f: as above, nn=duration)

E110 0fnn

Duration of Œ (f: as above, nn=duration)

E110 1x0x

Reserved

E110 1f1b

Date (/time) of Œ  (f,b: as above)

E111 0nnn

Multiplicative correction factor: 10nnn-6

E111 10nn

Additive correction constant: 10nn-3 · unit of VIF (offset)

E111 1100

Reserved

E111 1101

Multiplicative correction factor for value (not unit): 103

E111 1110

future value

E111 1111

next VIFE's and data of this block are maufacturer specific

Table 13: Combinable (orthogonal) VIFE-Table

Note that this optional table has been added to the original standard.

 

Notes:

Œ "Date(/time) of" or "Duration of" relates to the information which the whole data record header contains.

 The information about usage of data type F (date and time) or data type G (date) can be derived from the datafield (0010b: type G / 0100: type F).

65 Application Layer Status and error reporting

The data link layer reports only communication errors by means of omittingleaving out the acknowledgement $E5 or a via a negative acknowledgement. It is not allowed to report errors of the application layer (which can occur for example in data writing) via the link layer. The slave can transmit an $E5 after a SND_UD to indicate that it has received the telegram, but can´t respond with data. There are three different techniques for reporting application errors:

65.1 Status Field

One possible solution is to use the reserved 2 lowest bits of the Status field in the variable data structure for the application layer status (see Table 6).:

 

Fig. 5 Application Errors coded with the Status-Field

65.2 General Application Layer Errors

For reporting general application errors a slave can use a RSP_UD telegram with CI=$70 and zero, one or several data bytes, which then describes the type of error:

68h

04h

04h

68h

08h

PAdr

70h

DATA

CS

16h

Fig. 6 Telegram for reporting general application errors

The following values for DATA are defined:

0

Unspecified error: also if data field is missing

1

Unimplemented CI-Field

2

Buffer too long, truncated

3

Too many records

4

Premature end of record

5

More than 10 DIFE´s

6

More than 10 VIFE´s

7

Reserved

8

Application too busy for handling readout request

9

Too many readouts (for slaves with limited readouts per time)

10..255

Reserved

Table 5 15 Codes for general application errors

Note that this optional table has been added to the original standard.

65.3 Record Errors

To report errors belonging to a special record the slave can use this data record header with a VIFE containing one of the following values to code the type of application error, which has been occured.

VIFE-Code

Type of Record Error

Error Group

E000 0000

None

 

E000 0001

Too many DIFE´s

 

E000 0010

Storage number not implemented

 

E000 0011

Unit number not implemented

 

E000 0100

Tariff number not implemented

DIF Errors

E000 0101

Function not implemented

 

E000 0110

Data class not implemented

 

E000 0111

Data size not implemented

 

E000 1000 to

E000 1010

Reserved

 

E000 1011

Too many VIFE´s

 

E000 1100

Illegal VIF-Group

 

E000 1101

Illegal VIF-Exponent

VIF Errors

E000 1110

VIF/DIF mismatch

 

E000 1111

Unimplemented action

 

E001 0000 to

E001 0100

Reserved

 

E001 0101

No data available (undefined value)

 

E001 0110

Data overflow

 

E001 0111

Data underflow

 

E001 1000

Data error

Data Errors

E001 1001 to

E001 1011

Reserved

 

E001 1100

Premature end of record

 

E001 1101

to

E001 1111

Reserved

Other Errors

Table 6 16: Codes for record errors (E = extension bit)

Note that this optional table has been added to the original standard.

In case of record errors the data maybe invalid. The slave has some options to transmit the data:

· datafield = 0000b: no data

· datafield = 0000b: no data and idle filler (DIF=$2F): fill telegram record up to the normal length

· other datafield: dummy data of correct length

· other datafield: unsafe or estimated data

76 Generalized Object Layer

The fundamental idea of an object is the encapsulation of data and methods or actions for the data. In case of writing data to a slave the master software can pack data and information about the action, which the slave shall do with this data, in one data record. This variable data record with actions is now called an object. Following any VIF including a VIF=$FD or VIF=$FB with the true value information in the first VIFE another (usually the last) VIFE can be added which contains a code signalling object actions according to the following table.

Action: (E: extension bit)

VIFE-Code binary

Action

Explanation

E000 0000

Write (Replace)

replace old with new data