AEG SEAB-1F : Telegram structure

 

Bit serial transmission of the particular telegram bytes

A telegram consists of one or more 11 bit elements, 1 start bit, 8 bits information ( byte ), 1 parity bit and 1 stop bit. During serial transmission the bit with the lower value is first transmitted.

 

 

Long telegram

The telegram with variable length is used for the data transmission of the user data between the master station and the substation and in the reversed direction. It is distinguished between 4 types of long telegrams.

 

 

 

Address ( A ) :

Station address : 1 ... 127
The station address 127 is used as broadcast address. With it all substation on a line can be addressed simultaneously. Telegrams with broadcast address are not acknowledged. In short telegrams the broadcast address is not allowed.

 

Function instruction ( F ) :

The function byte consists of information to the mode of operation for the downstreamed process units and allows the identification of the message type.

 

7 6 5 4 3 2 1 0

<-- Bit number

              0

0 = Monitoring direction

              1

1 = Control direction

          0 0  

Telegram format : 00 = no data bytes

          0 1  

01 = 2 data bytes ( D1, D2 )

          1 0  

10 = n data bytes ( D1, D2, D3, D4, ... Dn )

          1 1  

11 = 4 data bytes ( D1, D2, D3, D4 )

        0      

Bit 4 ... 7 for the transmission control unit

        1      

Bit 4 ... 7 for the process unit

Control direction :

0 0 0 0 1 0 1 x

 0 : Request indications

0 0 0 1 1 0 1 x

 1 : Request measurands ( 8 bit )

0 0 1 0 1 0 1 x

 2 : Request counters

0 0 1 1 1 0 1 x

 3 : Request fleeting messages ( DOLOG )

0 1 0 0 1 0 1 x

 4 : Request measurands ( 16 bit )

0 1 0 1 1 0 1 x

 5 : Request indications ( with time tag )

0 1 1 0 1     x

 6 : reserved

0 1 1 1 1     0

 7 : not used

1 0 0 0 1     1

 8 : reserved

1 0 0 1 1 0 1 1

 9 : Impulse command

1 0 1 0 1 0 1 1

10 : Duration command

1 0 1 1 1 0 1 1

11 : (BB) Command ( DOLOG )

1 1 0 0 1 0 1 1

12 : Setpoint command

1 1 0 1 1     1

13 : reserved

1 1 1 0 1     1

14 : reserved

1 1 1 1 1     1

15 : Administration commands

Monitoring direction :

x 0 0 0 1 0 1 x

 0 : Indications

x 0 0 1 1 0 1 x

 1 : Measurands ( 8 bit )

x 0 1 0 1 0 1 x

 2 : Counters

x 0 1 1 1 0 1 x

 3 : Fleeting indications ( DOLOG )

x 1 0 0 1 0 1 x

 4 : Measurands ( 12/ 16 bit )

x 1 0 1 1     x

 5 : Indications w/o time tag ( type 1 )
      Indications with time tag ( type 3 )

x 1 1 0 1     x

 6 : reserved

x 1 1 1 1     0

 7 : Administration messages

 

0       1     0

0 = requested transmission ( only single request )

1       1     0

1 = spontaneous transmission

 

Sub-address ( A1 ) :

The subaddress byte contains 256 subaddresses relating to the given operation mode in the operating instructions.

 

Block length ( F1 ) :

 

 

Block identification ( F2 ) :

 

 

Data bytes ( D1 ... Dn ) :

Except for administration commands/ administration messages the data field is used for the code transparent transmission of process data. In this way e. g. binary single information ( commands/ messages ) or dual-coded information ( measurands/ counters, time, ... ) can be transmitted.
For particular administration telegrams D1 and D2 are fixed coded.

 

Security byte ( S ) :

 

 

Quick scan / RTU quittance ( single character )

The short telegram is provided for services of the link layer. This format is used as request or acknowledge in both directions.

Send request : In party line operation the master requests the substation to send the spontaneous data.

Quittance from the master to the slave : As acknowledge to the slave for telegrams received from the slave and at the same time as further send request.

Quittance from the slave to the master : As acknowledge to the master for telegrams received from the master.

 

 

 


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LIAN 98 Protocol Router, Simulator and Analyzer
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