PROFIBUS Manual

Telegram sequences and time ratios

Telegram sequences and time ratios

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Telegram sequences and time ratios

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The field

SYN

designates the 33 bit synchronization pause.

 

The synchronization pause marks the beginning of a new telegram sequence.

 

Example of a sequence:

A master receives the token from its colleague:

SYN

SD4

DA

SA

 

It sends a telegram without a data field:

SYN

SD1

DA

SA

FC

FCS

ED

 

and receives a short confirmation in reply.

SC

 

The master sends another telegram without a data field:

SYN

SD1

DA

SA

FC

FCS

ED

 

and receives a telegram with variable length in reply:

SD2

LE

LEr

SD2

DA

SA

FC

PDU

FCS

ED

 

The master sends a telegram with variable length

SYN

SD2

LE

LEr

SD2

DA

SA

FC

PDU

FCS

ED

and receives no reply.

 

The master passes on control and sends a token telegram:

SYN

SD4

DA

SA