Description Of A Dp Cycle - Siemens SINUMERIK 840DiE sl Manual

01/2007
8.1.4

Description of a DP cycle

Actual values
Position controller
Setpoints
NC:
Master or position
controller
PROFIBUS DP
communication
Speed
control cycle
Drives:
DP slaves: 1 to 3
Fig. 8-2 Example: Optimized DP cycle with 3 DP 611U slaves
© Siemens AG 2007 All Rights Reserved
SINUMERIK 840Di sl Manual (HBIsl) – 01/2007 Edition
At time T , the current actual position values are read from all isochronous DP
I
slave drives. In the next DP cycle, the actual values are transferred to the DP
master in the time T .
DX
The NC position controller is started at the time T
putes the new speed setpoint for each axis on the basis of the position setpoint
and the transferred actual position value.
At the start of the next DP cycle, the speed setpoints are transferred from the
DP master to the DP slave drives in the time T
At time T , the speed setpoints are taken as new specified values for all drive
O
controllers.
T
M
T
DX
1
GC Dx Dx
DPV1 G T R
R R R R R
T
O
T
I
Key to Fig. 8-2:
T Master application cycle: NC position control cycle
MAPC
The following always applies for SINUMERIK 840Di sl: T
T DP cycle time: DP cycle time
DP
T Data exchange time: Sum of transfer times of all
DX
DP slaves
T Master time: Offset of the start time for NC
M
position control
8 PROFIBUS DP Communication
M,
.
DX
T T
MAPC = DP
R
T
Dx DPV1 GC Dx
G T R
R R R R R R
T
I
8.1 General
with T > T and com-
M DX,
DX
2
Dx Dx
R R R R R
T
O
= T
MAPC DP
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