Siemens SINAMICS S120 - Page 144

Communication via PROFIBUS
Motion control with PROFIBUS
4-144
E Siemens AG, 2004. All rights reserved
SINAMICS S120 Installation and Start-Up Manual, 12/04 Edition
Setting criteria for times
S Cycle (T
DP
)
–T
DP
must be set to the same value for all bus nodes.
–T
DP
> T
DX
and T
DP
 T
O
T
DP
is thus large enough to enable communication with all bus nodes.
Notice
After T
DP
has been changed on the PROFIBUS master, the drive system must be
switched on (POWER ON).
S T
I
and T
O
– Setting the times in T
I
and T
O
as small as possible reduces the dead time in
the position control loop.
–T
O
> T
DX
+ T
Omin
S A tool is available for settings and optimization.
– Allow a reserve.
Further class 2 masters can be connected.
Non-cyclic communication can take place.
Minimum time for reserve
Table 4-19 Minimum time for reserve
Data
Time required [ms]
Basic load 300
Per slave 20
Per byte of user data 1.5
One additional class 2 master 500