Спецификация протокола Profibus

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PROFIBUS-Specification-Normative-Parts-3:1997

1 Scope

(see Part 2)

2 Normative References

(see Part 2)

3 General

(see Part 2)

4 PROFIBUS Layer 2 Interface

The following subsections abstractly describe the data transfer (FDL = Fieldbus

Data Link) and the management (FMA = Fieldbus Management) services of PROFIBUS.

The FDL services are made available to the user via Layer 2. The FMA1/2 services

are made available through the management (FMA1/2) associated with Layers 1 and

2. Neither the implementation of the controllers nor the hard-, firm- or soft-

ware interfaces are specified or prescribed.

4.1 FDL User - FDL Interface

This clause describes the data transfer services available to the FDL user with

their service primitives and their associated parameters. These services of the

FDL are optional.

FDL User

----------- +=====================+---------+

! ! !

Layer 2 ! FDL ! !

! ! !

! ! FMA1/2 !

----------- +---------------------+ !

! ! !

Layer 1 ! PHY ! !

! ! !

----------- +--------+---+--------+---------+

---------+ +-------------------

"Layer 0" Physical Medium

---------------------------------

Figure 1. Interface between FDL User and FDL in Relation to Layer Model

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4.1.1 Overview of Services

The user of Layer 2 is provided with the following data transfer services:

- Send Data with Acknowledge (SDA)

- Send Data with No Acknowledge (SDN)

- Send and Request Data with Reply (SRD)

- Cyclic Send and Request Data with Reply (CSRD)

Send Data with Acknowledge (SDA)

This service allows a user of the FDL (Layer 2) in a master station (called

Local User in the following), to send user data (Link_service_data_unit, L_sdu)

to a single remote station. At the remote station the L_sdu, if received error-

free, is delivered by the FDL to the user (called Remote User in the following).

The Local User receives a confirmation concerning the receipt or non-receipt of

the user data. If an error occurred during the transfer, the FDL of the Local

User shall repeat the data transfer.

Send Data with No Acknowledge (SDN)

This service allows a Local User to transfer data (L_sdu) to a single remote

station, to many remote stations (Multicast), or to all remote stations (Broad-

cast) at the same time. The Local User receives a confirmation acknowledging the

end of the transfer, but not whether the data was duly received. At the remote

stations this L_sdu, if received error-free, is passed to the Remote User. There

is no confirmation, however, that such a transfer has taken place.

Send and Request Data with Reply (SRD)

This service allows a Local User to transfer data (L_sdu) to a single remote

station and at the same time to request data (L_sdu) that was made available by

the Remote User at an earlier time. At the remote station the received L_sdu, if

error-free, is passed to the Remote User. The service also allows a Local User

to request data from the Remote User without sending data (L_sdu = Null) to the

Remote User.

The Local User receives either the requested data or an indication that the data

was not available or a confirmation of the non-receipt of the transmitted data.

The first two reactions also confirm the receipt of the transferred data.

If an error occurs during the transfer, the FDL of the Local User repeats the

data transfer with the data request.

Cyclic Send and Request Data with Reply (CSRD)

This service allows a Local User to cyclically transfer data (L_sdu) to a remote

station and at the same time to request data from the remote station. At the re-

mote station the data received error-free is passed cyclically to the Remote

User. The service also allows a Local User to cyclically request data from the

Remote User without sending data to the Remote User.

The Local User cyclically receives either the requested data or an indication

that the data was not available or a confirmation of the non-receipt of the

transmitted data. The first two reactions also confirm the receipt of the trans-

ferred data.

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If an error occurs during the transfer, the FDL of the Local User repeats the

data transfer with the data request.

The selected remote stations and the number and sequence of the data transfers

with data requests for the cyclic mode shall be defined by the Local User in the

Poll List.

4.1.2 Overview of Interactions

The services are realized by using a number of service primitives (denoted by

FDL_...). To request a service the user employs a Request primitive. A Confirma-

tion primitive is returned to the user upon completion of a service, or in the

case of services with cyclic repetition, after every send/request cycle. If an

unexpected event occurs at the remote station, the Remote User is informed by an

Indication primitive. For the services mentioned above the following primitives

apply:

Possible for the

following stations

Send Data with Acknowledge (SDA)

FDL_DATA_ACK.request Master

FDL_DATA_ACK.indication Master and Slave

FDL_DATA_ACK.confirm Master

Send Data with No Acknowledge (SDN)

FDL_DATA.request Master

.indication Master and Slave

.confirm Master

Send and Request Data with Reply (SRD)

FDL_DATA_REPLY.request Master

.indication Master and Slave

.confirm Master

FDL_REPLY_UPDATE.request Master and Slave

.confirm - " -

Cyclic Send and Request Data with Reply (CSRD)

FDL_SEND_UPDATE.request Master

.confirm - " -

FDL_CYC_DATA_REPLY.request Master

.confirm - " -

FDL_CYC_ENTRY.request Master

.confirm - " -

FDL_CYC_DEACT.request Master

.confirm - " -

FDL_DATA_REPLY.indication Master and Slave

FDL_REPLY_UPDATE.request Master and Slave

.confirm - " -

confirm: confirmation

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Temporal Relationships of Service Primitives:

Notation in the following figures:

.req .request

.ind .indication

.con .confirmation

L_sdu Link_service_data_unit

L_pci Link_protocol_control_information

L_pdu Link_protocol_data_unit

L_pdu L_pci + L_sdu

Master Master/Slave

Station Station

1 n

! !

FDL_DATA_ACK.req ! !

------------------>! - _(L_pdu) !

(L_sdu) ! - _ ! FDL_DATA_ACK.ind

! - !----------------->

! _ - ! (L_sdu)

FDL_DATA_ACK.con ! _ -(L_pdu) !

<------------------! !

! !

Figure 2. SDA Service

Master Master/Slave

Station Station

1 2 3 4 n

! ! ! ! !

FDL_DATA.req ! (L_pdu) ! ! ! !

-------------->!-- _ ! ! ! !

(L_sdu) ! ) - _ ! ! ! !

! ) !---> ! ! !

FDL_DATA.con ! ) ! !---> ! !

<--------------!<- ! ! !---> ! FDL_DATA.ind

! ! ! ! !------------->

! ! ! ! ! (L_sdu)

! ! ! ! !

Figure 3. SDN Service

Master Master/Slave

Station Station

1 n

! ! FDL_REPLY_UPDATE.req

! --!<---------------------

! ( ! (L_sdu)

! ( !

! ( ! FDL_REPLY_UPDATE.con

! --!--------------------->

FDL_DATA_REPLY.req ! !

-------------------->! - _(L_pdu) !

(with/without L_sdu) ! - _ ! FDL_DATA_REPLY.ind

! - !------------------->

! _ - ! (with/without L_sdu)

FDL_DATA_REPLY.con ! _ -(L_pdu) !

<--------------------! !

(L_sdu) ! !

! !

Figure 4. SRD Service

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Master Master/Slave

Station Station

1 2

FDL_CYC_DATA_REPLY.req ! !

------------------------>!-- !

! ) !

FDL_CYC_DATA_REPLY.con ! ) !

<------------------------!<- !

! !

FDL_SEND_UPDATE.req ! !

--------------------->!-- !

! ) !

FDL_SEND_UPDATE.con ! ) !

<---------------------!<- !

: ! !

: !

! FDL_REPLY_UPDATE.req

FDL_CYC_ENTRY.req ! --!<--------------------

------------------->!-- ( !

! ) ( ! FDL_REPLY_UPDATE.con

FDL_CYC_ENTRY.con ! ) ->!--------------------->

<-------------------!<- !

! - _ !

! - _ ! FDL_DATA_REPLY.ind

! - !------------------->

! _ - !

FDL_CYC_DATA_REPLY.con ! _ - !

<------------------------!

! 3

! ! FDL_REPLY_UPDATE.req

FDL_CYC_ENTRY.req ! --!<---------------------

------------------->!-- ( !

! ) ( ! FDL_REPLY_UPDATE.con

FDL_CYC_ENTRY.con ! ) ->!--------------------->

<-------------------!<- !

! - _ !

! - _ ! FDL_DATA_REPLY.ind

! - !------------------->

! _ - !

FDL_CYC_DATA_REPLY.con ! _ - !

<------------------------!

! n

! ! FDL_REPLY_UPDATE.req

FDL_CYC_ENTRY.req ! --!<---------------------

------------------->!-- ( !

! ) ( ! FDL_REPLY_UPDATE.con

FDL_CYC_ENTRY.con ! ) ->!--------------------->

<-------------------!<- !

! - _ !

! - _ ! FDL_DATA_REPLY.ind

! - !------------------->

! _ - !

FDL_CYC_DATA_REPLY.con ! _ - !

<------------------------! !

! !

V V

Figure 5a. Start of CSRD Service

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V V

! !

Master Master/Slave

Station Station

1 2

! !

FDL_SEND_UPDATE.req ! a new Poll List Cycle

--------------------->!--

! ) !

FDL_SEND_UPDATE.con ! ) !

<---------------------!<- ! FDL_REPLY_UPDATE.req

: ! --!<---------------------

: ! ( !

: ! ( ! FDL_REPLY_UPDATE.con

: ! ->!--------------------->

: ! !

! - _ !

! - _ ! FDL_DATA_REPLY.ind

! - !------------------->

! _ - !

FDL_CYC_DATA_REPLY.con ! _ - !

<------------------------!

! 3

! ! FDL_REPLY_UPDATE.req

! --!<---------------------

! ( !

! ( ! FDL_REPLY_UPDATE.con

! ->!--------------------->

! !

! - _ !

! - _ ! FDL_DATA_REPLY.ind

! - !------------------->

! _ - !

FDL_CYC_DATA_REPLY.con ! _ - !

<------------------------!

! n

! ! FDL_REPLY_UPDATE.req

! --!<---------------------

! ( !

! ( ! FDL_REPLY_UPDATE.con

! ->!--------------------->

! !

! - _ !

! - _ ! FDL_DATA_REPLY.ind

! - !------------------->

! _ - !

FDL_CYC_DATA_REPLY.con ! _ - !

<------------------------! !

! !

FDL_CYC_DEACT.req ! !

------------------->!-- !

! ) !

FDL_CYC_DEACT.con ! ) !

<-------------------!<- !

! !

Figure 5b. End of CSRD Service

4.1.3 Detailed Specification of Services and Interactions

4.1.3.1 Send Data with Acknowledge (SDA)

The Local User prepares a Link_service_data_unit (L_sdu) for the Remote User

that contains transparent process information (e. g. data or commands) from the

PROFIBUS for the FDL and PHY. This data is passed to the local FDL controller

via the FDL interface by means of a FDL_DATA_ACK.request primitive.

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The FDL controller accepts the service request and tries to send the L_sdu to

the remote FDL controller (for the message format see Part 4, Table 3a, b7=1,

Code No 3/5). The local FDL controller passes a confirmation to the Local User

by means of the FDL_DATA_ACK.confirm primitive that signals either correct or

erroneous data transfer.

Prior to passing a confirmation to the Local User, the local FDL controller

needs an acknowledgement from the remote FDL controller (see Part 4, Table 3a,

b7=0, Code No 0/1/2/3 or SC = E5H). If this acknowledgement is not received

within the Slot Time T

SL

(see Part 4, subclause 4.1.7), the local FDL controller

shall try again (Retry) to send the L_sdu to the remote FDL. If no acknow-

ledgement is received after n retries (max_retry_limit), the local FDL control-

ler shall signal a negative acknowledgement to the Local User. During the trans-

fer of the data and the receipt of the associated acknowledgement, no other

traffic takes place on the PROFIBUS.

If the data frame was received error-free, the remote FDL controller passes the

L_sdu to the Remote User via the FDL user interface by means of a FDL_DATA_ACK.

indication primitive.

Parameters of the primitives:

FDL_DATA_ACK.request

(SSAP, DSAP, Rem_add, L_sdu, Serv_class)

- The parameter SSAP (Source Service Access Point) defines the service access

point of the Local User. The Local User Access Address (see Part 4, subclause

4.8.2.2) identifies the SSAP. The SSAP value 63 (Global Access Address) is

not permissible.

- The parameter DSAP (Destination Service Access Point) defines the service ac-

cess point of the Remote User. The Remote User Access Address (see Part 4,

subclause 4.8.2.2) identifies the DSAP.

PROFIBUS stations that do not carry LSAPs in the frames for efficiency reasons,

set both the parameters SSAP and DSAP to NIL; this means that the Default LSAP

is addressed (see Part 4, subclause 4.8.2.2).

- The parameter Rem_add (Remote_address) defines the FDL address of the remote

station (Destination Address DA, DAE[b7=1], as defined in Part 4, subclause

4.8.2). Rem_add needs to be an individual address. The global address is not

permissible.

- The parameter L_sdu (Link_service_data_unit) contains the user data that is

to be transferred by the FDL controller. The L_sdu contains 1 octet as the

minimum data unit, the maximum length is 246 octets. When using SSAP, DSAP

and Region/Segment Addresses, a maximum of 242 octets is possible.

- The parameter Serv_class defines the FDL priority for the data transfer. Two

priorities are possible (see Part 4, subclause 4.1.1.5 and Table 3a):

High Priority (high): Time-critical messages, such as alarms, synchroniza-

tion and coordination data.

Low Priority (low): Less urgent messages, such as process, diagnostic,

program data.

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This primitive is passed from the Local User to the local FDL controller to send

data using Send_Data_with_Acknowledge to a Remote User. Receipt of the primitive

results in the transmittal of the L_sdu by the local FDL controller employing

the SDA procedure. While processing a SDA Request (i. e. while waiting for the

acknowledgement) no further SDA or SDN or SRD shall be sent from the local FDL

controller.

FDL_DATA_ACK.indication

(SSAP, DSAP, Loc_add, Rem_add, L_sdu, Serv_class)

- The parameters SSAP and DSAP specify the Source and Destination Service Ac-

cess Point of the received SDA frame (see Part 4, subclause 4.8.2.2).

- The parameters Loc_add (Local_address) and Rem_add specify the source FDL ad-

dress (SA, SAE[b7=1]) and the destination FDL address (DA, DAE[b7=1]) of the

received SDA frame (see Part 4, subclause 4.8.2). The global address is not

permissible in either case.

- The parameter L_sdu contains the Local User data of the received SDA frame.

- The parameter Serv_class specifies the FDL priority of the received SDA

frame.

This primitive is passed from the remote FDL controller to the Remote User after

receipt of a SDA frame, if the acknowledgement frame was sent. The reaction of

the Remote User upon receipt of this primitive is not specified. In case of

repetition of the acknowledgement frame, caused by the receipt of a repetition

of the SDA frame, the Indication primitive shall not be repeated.

FDL_DATA_ACK.confirm

(SSAP, DSAP, Rem_add, Serv_class, L_status)

- The parameter SSAP specifies the service access point of the Local User. An

SSAP-value of 63 is not permissible.

- The parameter DSAP specifies the service access point of the Remote User.

- The parameter Rem_add specifies the destination FDL address (DA, DAE[b7=1])

of the SDA frame. The global address is not permissible.

- The parameter Serv_class specifies the FDL priority of the associated data

transfer.

- The parameter L_status indicates success or failure of the preceding SDA

request and whether a temporary or a permanent error exists. The following

parameter values are specified:

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Table 1. SDA, Values of L_status

+----+--------------------------------------------+-----------+

!Code! Meaning ! temporary/!

! ! ! permanent !

+----+--------------------------------------------+-----------+

! OK ! Positive acknowledgement, service finished ! - !

! RR ! Negative acknowledgement, resources of the ! !

! ! remote FDL controller not available or not ! !

! ! sufficient. ! t !

! UE ! Negative acknowledgement, remote FDL User/ ! !

! ! FDL interface error. ! p !

! RS ! Service or Rem_add at remote LSAP or remote! !

! ! LSAP not activated (see subclause 4.2.3.7).! p !

! LS ! Service at local LSAP or local LSAP not ! !

! ! activated. ! p !

! LR ! Resources of the local FDL controller not ! !

! ! available or not sufficient. ! t !

! NA ! No or no plausible reaction (Ack./Res.) ! !

! ! from remote station. ! t !

! DS ! Local FDL/PHY controller not in logical ! !

! ! token ring or disconnected from line. ! p !

! IV ! Invalid parameters in request. ! - !

+----+--------------------------------------------+-----------+

This primitive is passed as an indication from the local FDL controller to the

Local User upon completion of the requested SDA service. The reaction of the

Local User upon receipt of this primitive is not specified. When L_status indi-

cates a temporary error, the Local User may assume that a subsequent repetition

may be successful. In case of a permanent error, management should be consulted

prior to repetition of the service. In case of the local errors LS, LR, DS and

IV no request frame is transmitted.

4.1.3.2 Send Data with No Acknowledge (SDN)

The Local User prepares a L_sdu for a single, for a group of, or for all Remote

Users. The L_sdu is passed to the local FDL controller via the FDL interface by

means of a FDL_DATA.request primitive. The FDL controller accepts the service

request and tries to send the data to the remote FDL controller requested, to

the group, or to all stations (see Part 4, Table 3a, b7=1, Code No 4/6).

The FDL controller returns a local confirmation of transmittal to the Local User

by means of a FDL_DATA.confirm primitive.

There is no guarantee of correct receipt at the remote FDL controllers, as nei-

ther acknowledgements are given nor local retries take place. Once the data is

sent it reaches all Remote Users at the same time (not taking into account sig-

nal propagation time). Each addressed remote FDL controller that has received

the data error-free passes it to the FDL user by means of a FDL_DATA.indication

primitive.

Parameters of the primitives:

FDL_DATA.request

(SSAP, DSAP, Rem_add, L_sdu, Serv_class)

- The parameters have the same meaning as described for SDA under the

FDL_DATA_ACK.request primitive. Exception: the global address (Broadcast/

Multicast message) is not permitted for Rem_add. For broadcast messages a

DSAP value of 63 shall be chosen. In case of multicast messages the selection

(group of stations) is performed by means of a dedicated DSAP.

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This primitive is passed from the Local User to the local FDL controller to send

data using Send_Data_with_No_ Acknowledge to a single, a group of, or all Remote

Users. Receipt of the primitive causes the local FDL controller to transmit the

L_sdu by means of the SDN procedure.

FDL_DATA.indication

(SSAP, DSAP, Loc_add, Rem_add, L_sdu, Serv_class)

- The parameters have the same meaning as described for SDA under the

FDL_DATA_ACK.indication primitive corresponding to the received SDN frame.

Exception: the global address is permitted for Rem_add.

This primitive is passed from the remote FDL controller to the Remote User after

receipt of a SDN frame. The reaction of the Remote User upon receipt of this

primitive is not specified.

FDL_DATA.confirm

(SSAP, DSAP, Rem_add, Serv_class, L_status)

- The parameters SSAP, DSAP, Rem_add and Serv_class have the same meaning as

described for SDA under the FDL_DATA_ACK.confirm primitive corresponding to

the SDN frame. Exception: the global address is permitted for Rem_add.

- The parameter L_status indicates local success or failure of the associated

SDN request. The following parameter values are specified:

Table 2. SDN, Values of L_status

+----+--------------------------------------------+-----------+

!Code! Meaning ! temporary/!

! ! ! permanent !

+----+--------------------------------------------+-----------+

! OK ! Transmission of data completed by local ! !

! ! FDL/PHY controller. ! - !

! LS ! Service in local LSAP or local LSAP not ! !

! ! activated. ! p !

! LR ! Resources of the local FDL controller not ! !

! ! available or not sufficient. ! t !

! DS ! Local FDL/PHY controller not in logical ! !

! ! token ring or disconnected from line. ! p !

! IV ! Invalid parameters in request. ! - !

+----+--------------------------------------------+-----------+

This primitive is passed from the local FDL controller to the Local User as an

indication upon completion of the requested SDN service. The reaction of the

Local User upon receipt of this primitive is not specified. When L_status indi-

cates a temporary error, the Local User may assume that a subsequent repetition

may be successful. In case of a permanent error, management should be consulted

prior to repetition of the service. In case of the local errors LS, LR, DS and

IV no request frame is transmitted.

4.1.3.3 Send and Request Data with Reply (SRD)

The Local User prepares a L_sdu for the Remote User. The data is passed to the

local FDL controller via the FDL interface by means of a FDL_DATA_ REPLY.request

primitive, requesting data from the Remote User at the same time. The FDL con-

troller accepts this combined service request and tries to send the L_sdu

together with a data request to the remote FDL controller (see Part 4, Table 3a,

b7=1, Code No 12/13). If no data is to be sent at the Local User's end, he may

use the service employing the same primitive as an exclusive data request.

Спецификация протокола Profibus

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