Parameters and properties
43
SIPROTEC PROFIBUS-DP - Communication profile
C53000-L1840-B001-03
2.5.3 Handshake mechanism
Note:
A number of PROFIBUS-DP bus cycles may occur between a new telegram from the
PROFIBUS-DP slave and the evaluation of its data (message blocks, setting of the
control bytes) by the PROFIBUS-DP master (as well as the other way around), i.e. the
arrows do not mark one bus cycle, but the direction of the superseding telegram
exchange.
PROFIBUS-DP slave
PROFIBUS-DP master
(SIPROTEC device)
Master and slave with cyclic data exchange,
For this example: three message blocks were transferred and acknowledged by the master,
current message block number is 14
dec
= E
hex
Only one entry in the event list still exist:
• Entry form the event list is copied to the mes-
sage block #1 in the telegram,
• Message blocks #2 and #3 are filled with zeros,
• “Control_I” = F0
hex
(Message block no. + 1),
• Current annunciations, measured values,
metered values are entered in the telegram.
• Evaluation of the cyclic annunciations,
measured values and metered values,
• Master recognises change in “Control_I”:
evaluation of the message blocks,
• “Control_O” = “Control_I” = F0
hex,
• If required, control information to SIPROTEC
device.
Slave recognises acknowledgement in “Control_O”.
There are no entries in the event list:
• “Control_I” remains = F0
hex,
• Message blocks #1 to #3 are filled with zeros,
• Current annunciations, measured values,
metered values are entered in the telegram.
• Evaluation of the cyclic annunciations,
measured values and metered values,
• No action regarding the message blocks, as no
change in the message block number,
• “Control_O” = “Control_I” = F0
hex,
• If required, control information to SIPROTEC
device.
There are 4 new entries in the event list:
• The first 3 entries from the event list are
copied to the message blocks #1 to #3 of the
telegramm,
• “Control_I” = 10
hex
(Message block no. + 1),
• Current annunciations, measured values,
metered values are entered in the telegram.
• Evaluation of the cyclic annunciations, measured
values and metered values,
• Master recognises change in “Control_I”:
evaluation of the message blocks,
• “Control_O” = “Control_I” = 10
hex,
• If required, control information to SIPROTEC de-
vice.
There are 2 entries in the event list (one “old”
from the abovementioned 4 plus one new entry):
• Entries from event list are copied to the
message blocks #1 and #2 of the telegram,
• Message block #3 is filled with zeros,
• “Control_I” = 20
hex
(Message block no. + 1),
• Current annunciations, measured values,
metered values are entered in the telegram.
. . .
To Next Page
Loading...
Need help?
General